Hi, I would post up on the impactbumpers.com website as guys over there are far more experienced on the models. I had an 83 SC coupe which was 3.0 lt with 915 box, although box was in superb order it could not be rushed and needed to be thoughtfully driven. Loved it and ran for 10 years with no issues. Replaced it with a 3.2 Speedster with G50 box, a totally different drive with a positive change and one you could easily get in and drive without really thinking of the gear change. Everything else was same, no abs,traction or power steering. Great cars and enjoyed all the years I owned them, now replaced with a 996 X50 turbo cab, totally different but so much more usable for me, personal view obviously, but having driven the air cooled for over 20 years loving the relatively new creature comforts (old age,me I mean😀)
They are both superb cars but in different ways, I would drive both and then decide whip suits your driving. However check for RUST! it's surprising how it can hide
Good luck