IMO, this is a big performance item most drop the ball on in vintage. Most are too infatuated with horsepower.
That said, it's one of those things where the better / more aggressive driver you are, the bigger difference they make. If you're driving at 9.9/10 (it's vintage
), bounce off curbs, use the rumble strips, etc. Then they will make a huge difference. A lot of people are too slow to really notice a decent set of shocks from a really good set of shocks. Horsepower is noticeable at any talent level.
The only thing governing shocks is remote reservoirs are illegal. There are ways around that.
Bilsteins are good, and they have more than just the street stuff. Afcos work very well if you find the right person to valve them (most are circle track guys, so you need to find someone with road racing experience). Ohlins is the cream-of-the-crop.