NASA PRO-7/PS-7 rule explanations
 

What is the undercoating that can be removed? Also, what modifications do i need to do if any to fit the 81-85 Complete front Mac Pherson strut assembly (my car is a 1980)

the undercoating is the thick tar crud on the floorboards.

NASA cancelled the Pro7 class (and several other older spec classes like GTI Cup) and blended the cars into Pro Touring.

PS-7 was SCCA ITA rules but only 1st gen rx7's. AFAIK that class's been blended into Pro Touring too.

I belive the only thing you have to look out for in swapping the front suspension in the thread pitch on the brake lines and calipers. If I remember right 79-80 was course and 81-85 was fine.