"...Pontiac V8 a corporate motor?..."
Don't think I've ever read the current GT rules. If I have I don't remember all of 'em.
So, does it say specifically that only "corporate" motors can be used in GT ?
If so, in order to be considered "corporate", did the engine have to be available in every GM division, which I assume would include Chevy, Pontiac, Olds, Buick, & Cadillac ???
If so, I suppose that would eliminate quite a few GM engines. Probably would ban all BBC engines, from non-Chevy car bodies. ???
OR, do the GT rules allow any GM engine in any GM body ???
I don't know. I'm just askin.
As for questionable combos, I reckin it's pretty much left up to the tech guys at any particular race. Most are obviously not near as picky as they once were.
I can think of a popular car that has no front turn signal lamps. I have been scolded online for even mentioning that.
Another popular Bird, running as a '73, IIRC, actually has '71 Firebird fenders on it. But it has been running for years like that, & has passed tech.
I think several of the early '70's Birds have got by with just changing grills, when claiming different year models. I personally don't think those small changes should make any difference. BUT, I can remember back when Wesley would bounce a car for VERY minor infractions. Obviously, the rules are a lot more lax, nowadays, at least for most tech guys.
Some guys want the rules strictly enforced. Others want 'em lax, so more cars can run in the Stock & SS classes, to help keep 'em alive.
Opinions differ.
The Bird below has a Formy hood, with TA fenders, in the 1st pic. Then in the 2nd pic, it has T/A hood & fenders, but no wheel flairs. It passed tech, in both conditions. So, those items apparently don't matter nowadays. I don't know, Just a casual observation. IMO, those items would not affect performance in a noticeable way. But, cars have been bounced for less, in days gone by.