If you original engine was tired like mine, it was probably only kicking out about 95bhp, even if it ran beautifly (mine does)!
If you want to keep it original, I seriously think with a ported head, higher compresion runing the original management you would be looking at near 130-140bhp
which would make it very lively.
Otherwise if you don't want to keep it original, skys the limit!
I'm a little worried about originality, but at the same time like performance, so as a compremise if I alter mine, I will keep all the original stuff to give the next owner the choice
These cars have a lot of history and class, so it's tricky modding them, as you could get carried away and forget about their heritage. But at the same time, your dealing with wires and stuff which is 23+ years old.....