i have a lead on a 75 351w. i need to know what numbers to look for. basicly i want to identify the motor i don't know the guy, friend of a friend thing. also this is ganna be a cheap build up. only ganna throw in a cam intake and new carb. any comments on the heads from these years? i have access to a pair of 88gt heads will these interchange and is it worth it? thanks alot