To answer your question regarding Oldsmobile engines in a Pontiac, 
 This was done with several GM Brands during the late 70's to early 
 80's (some of you gear heads may remember this got GM into an 
 ugly law suit...and they paid dearly) 
 Another example I can vouch for , a close friend bought '77 Olds 
 "98" (Loaded with every option,and yepa Chev. 350!!! 
 He was furious!! (Rumor had it he neutered his salesman.)lol 
 Seriously though he was in on that GM class action suit. 
 Thanks for the memories GM !