My experience ALL comes from the M-body...but the M-body coupes are pretty much what the F-body coupes are. The suspension, etc, etc interchange.

As some have pointed out the difficulty in this would be sourcing the interior stuff and finding it in a shape that is still usable. My '80 coupe (being made for 2 yrs only, and is different from the '78-'79 yrs) was VERY difficult to source parts for. No aftermarket existed (still doesn't for the most part).

Having said that, stuff like weatherstripping (doors and roof-rail) is now finally available...for me that was by far the hardest part to get...eventually I made the F-coupe work on my ride (took a little custom work...lol).

The suspension is easy stuff...lots of parts to upgrade with, and best of all, aftermarket, the original Moog/TRW/etc parts are there for the HD options...so if you want to run the big brakes, the big tie-rods, etc, it's just a matter of finding the right part number and ordering the stuff from the likes of RockAuto. The K-frame biscuits are easily replaced with either POLY or aluminum...these are readily available. If you want to go a little extreme you can even go custom T-bar way, one of the other M-body guys on here has done that.

So in a sense it all depends what you want your car to be about? I do enjoy driving mine and being told by folks I strike up a conversation with: "...I had no idea they made the Diplomat in coupe style...", or "...wow, I had one like that once, but I never see them around anymore...", in other words, I wanted something different.