I know that the most exciting version that is still imitated today is the sky high straight axle fire breathers, but, depending on the class, most where pretty stock
Went to HL yesterday and they did have the Super Impala in stock, but not much else. And there are quite a few empty spots on the shelves, which hopefully means there is a reload on the way.
The Red sided vega in the pic is a recreation and runs on the nostalgia circuit, hence the engine being a bit newer.
https://tamrazs.wordpress.com/2017/01/04/the-midwest-nostalgia-pro-stock-association-recreates-pro-stock-past/
This is the restored Vega and engine