90.3 (purchase or lease from Boston College). Move antenna to One Financial Center (WHRB/WFNX/WERS site). 90.3 is short spaced to WGBH but I don't think that GBH would dispute their own service). This would cover the city. WCRB is now a non-comm so this could be done.
Oh my, where to begin? Okay, to start off I'll lay out the street cred - I was WZBC's (contract) Chief Engineer from 2003 to about 2006. I lived less than six blocks from their studios for two of those years, so I spent a lot of time there, both officially and unofficially.
WZBC lost any chance it had of realistically moving to a downtown skyscraper when WSMA was granted a CP. Theoretically, it CAN be done, but only by employing an unattractively low ERP (few hundred watts) and a very directional antenna.
WZBC
can move northward to higher ground...the old WFNX antenna in Malden or Zion Hill are good examples...and employ a directional antenna to protect WSMA and WICN and still increase both power and height to cover up towards the Merrimack Valley a LOT better. However, there's no benefit in terms of downtown (Boston/Cambridge) coverage from such a move, and it would increase their annual expenses. In fact, if anything their downtown coverage would get worse (there's a reason why WFNX was so hellbent to move to One Financial Center) and their campus coverage would go in the toilet. For a "college radio" station, it is politically a VERY bad move to have poor coverage on campus; it puts to lie the argument that you exist for the students' benefit. Whether that argument is really true or not is irrelevant; if you get money from the college (especially if it's from a Student Activity Fee, which I believe WZBC is) then you MUST claim that you serve the students.
There's also the issue that there's literally nowhere to put WZBC on the roof of OFC. There's no more room on the towers (I know the CE's of both WHRB and WERS and we've chatted extensively about this) and it was a major trick getting WFNX up there; required some clever antenna placement (i.e. expensive) and quite a lot of filtering (also expensive).
Also, things may have changed since 2006, but I doubt it, and that means WZBC has no ambitions to be anything more than it already is. In fact, they actively prefer the "fly under the radar" aspect of the operation.
And they've also recently invested a pretty penny on the existing transmitter site on top of Cheverus Hall of BC; that tower is - IIRC - less than 10 years old (15 at most), the antenna array, RF cabling, and transmitter were all bought and installed in 2003 (I did that with David Maxson) and they added proper HVAC to the transmitter closet in 2007 or 2008. The idea of paying all that money over again for a new transmitter site...and then paying tower rent...would cause jaws to hit the floor in the McElroy studios!!!
Finally, regardless of what WGBH would want for a move of WZBC, that wouldn't be enough. First, there's also WBUR to factor into the equation. Second, one reason the FCC denied WGBH's move to the Needham/Newton towers (i.e. FM-128, etc) was because of WZBC. That was DESPITE the explicit consent of WZBC to WGBH's plan. IIRC, the reasoning was that WGBH was not causing any new additional interference to WZBC that WZBC wasn't already receiving from WBUR and the blanketing interference from the other Needham/Newton tower stations. In fact, the new result would actually be decreased interference since the interference zone at Great Blue Hill would disappear. Problem was, the FCC didn't buy it - they decreed that ALL the new interference from WGBH alone at Newton/Needham would be counted, and when you counted it that way...it was an increase in the total population receiving interference to WZBC. WGBH *could* have reduced ERP to shrink the interference zone at Needham/Newton...but it was a pretty hefty decrease, IIRC. Something like going from 40kW ERP to 18. Shame, I would've liked to have the quid pro quo...
Oh yes, there's also the slight issue of the riots on campus and the community if BC ever tried to undercut WZBC like you propose. You might remember that UMass Lowell tried something similar with WUML and
that went rather badly for all parties involved. You should've seen the tension and threats flying back when the decision was made to hire a part-time professional GM for the station. The community DJ's were freaking out, the students were freaking out, and the listeners were freaking out. In that aspect, Judy was the perfect hire for that role - she's done an admirable job soothing the savage beasts while gradually moving WZBC towards overall betterment.
FWIW, I have been told that various religious broadcasters, in the past, have offered well north of seven figures to buy WZBC outright from BC, and they have consistently been rebuffed. You might say "that was before the economic crash of 2008 wrecked BC's budget" and that's true, but it also means that WZBC's value has fallen to the point where the political fallout is not worth the (relatively) small dollar value that a WZBC sale would bring. Not compared to the overall billions-dollar budget.