I can probably answer some of the questions you have about the original KBUC, since I worked there from 1982-84 just after Ricky Ware left and Tom East started doing mornings with Jud Ashmore.
KBUC was on 1310-AM daytime only and 107.5 24 hours when I was there. We played a mix of classic and current country and had a full service news department. The station was not owned by Sigmore, it was owned by the man who started Sigmore, Tom E. Turner. The company was called TETCO and it owned two stations in San Antonio (KBUC AM-FM), two in Belton and two in Corpus Christi along with Sigmore, Mission Trucking and had a stake in Bexar Savings Bank. Back in those days two stations per market was the maximum the FCC let anyone own. The talent line-up at the time was one of the best in the nation for any country station.
Mornings-Tom East-Jud Ashmore
Mid Morning-Ron Houston
Early Afternoon-Max Gardner
Afternoon Drive-Gene Kelly
Evenings-Mike Clay (and I was the news guy for the evening show)
As far as the discussions of 930 AM, it was never affiliated with KBUC. It started as KITE in the 60's and 70's and was the AM station that was affiliated with KEXL 104.5, which eventually became KITE-FM in the late 70's. It then switched to KCCW country and then to KRNN news talk in 1984 (which is the station I worked for after I left KBUC.) From there it switched to all talk in 1986 and eventually spanish before it became a MOR-Music of your Life station and now a news-talk once again, except now it's mostly satellite programming, when it was KRNN is was almost all local talk.
My dad was also in the San Antonio market (George Wood) from the late 50's to his death in 1990 so I have a pretty good knowledge of that time in San Antonio radio and TV. Let me know if you guys have any questions.