I finally found someone who is attempting to do what I am planning to do. AG and TLB are two of my favorite flicks, and the falfa car is one of the main reasons-- the RIchard Ruth aluminum 427 has got to be one of the sweetest sounding pounders on film.
Anyway, i was doing a search on the streetability of the 572 , since my son and I are going to build the AG version, complete with the chromed steel wheels, black paing and hanging skull. Our initial plan was to drop in a 502 ramjet. then we discussed (I guess I discussed, since he is only 6) the limited aluminum 454 from GM, and now we are looking at the 572. Since the 720hp version is a race fuel only beast, it is a real toss up -- since the 502 has a little over 500hp, vs the 572's 620. We want the "sleeper" quality of the original car, but want serious racey parts for the guts-- looking at a jerico 4spd drag box.

Your car looks great in the photo, I would really like to keep in touch, since you are obviously much farther along than we are. What i am most interested in is how easily the BB will drop into the nose of that beast with the headers.