Why don't you think your pointy Ergopower right hand lever is an 8-speed? That would change things.
There were several aluminum compact cranksets made by Campy: Veloce, Centaur, and I thought there may have been a Record, but not sure. The first two need a 111 mm BB while the Record if you find one needs 102 as has been said. A carbon Record compact is a super crankset, but a new 102 BB is an expensive item.
Seatposts: if you can find a Thomson that fits, get it. They are (check the numbers!!!) comparable in weight to most carbon and lighter than some, and the two-bolt saddle attachment allows you to do very fine adjustment of saddle angle and repeatible installations. And it's aluminum, which your vintage frame was designed for.