On paper, this sounds kinda frightening. But Mac did put out a really good 50s/rockabilly-inspired album back in 1999, "Run Devil Run", which featured his close pal David Gilmour (of Pink Floyd) on guitar. Included mostly cover tunes, the majority of them quite obscure. It wasn't a note-for-note exercise, he and his band left a very unique take on it. Probably his best album of the past two decades. It really rocks!
And yes, he did do a similar album for the Russian market about ten years earlier.
I assume this new album will be somewhat similar in nature, though I'm sure it's not going to be a rowdy rocker like "Run Devil Run". And I know that he's wary of venturing into Rod Stewart schmaltz territory. Sounds like it will be a bit more in the vocal jazz territory.