the question should be what do you need it to do? there are a million option's.
MCB will be your best source for info,but my advice would be to just keep it simple.
RVA,wedgits,delrin pump handle and thats about it. if it needs a rebuild pick up a valve tool and drop in a palmers dyna valve.
the pmi 1 was my second gun in about 89' and one of my fav's they have a great feel to them and I prefer them over a PGP.