Hey guys new to the site.... so hello!

I hope one of you guys can help me. I have a chance to buy a 1972 455 HO lemans convertible that has been rotisserie restored and is I believe the real deal. The engine is correct for the car but not matching, but he also has a complete */R blocked engine that is also available. The car is an automatic (sigh) and not completely finished from what I can see probably 80-90% done. I think it'* a money pit for him and becoming an irritant. My question is how much is this car worth? I cant seem to be able to find an evaluation, I believe it is a 1 of 33 car so it is rare, but whats it worth. Also he has PHS documentation, but it'* paper...is there any place on the car I can go to verify it is the real deal, I know vin tag and cowl tag are obvious but i would like maybe a place on the frame i could go to and see something stamped?

Any help would be greatly apprciated.

Thanks
Jack