If it's all nice and original, I would try to keep it that way, or only upgrade to things that would have been available at the time. Headlight levellers, electric mirrors etc.
16v suspension is a good choice and RA's work really well with big bumpers, but other than that I would leave it alone.
I'm not sure about the badges though. Even if they were on from new, it will look to everyone else that you put them on and are trying to make out that the car is something it's not. Does it have a badge on the glovebox lid and a bee sting aerial as well?