The essentials are a stronger nozzle and recoil spring. Don't go overboard on the spring. 120% is more than enough.
Depending on which make of slide you get, you may have to look at a metal barrel. I ran my TM with an Airsoft Masterpiece slide and the original plastic TM outer barrel for quite a while, without problems, but I don't know about other makes. Since the outer barrel on the Gold Match is non dropping, it will probably be fine with a metal slide.
I would always advise TM hi capa owners to get an AM slide. They are nicely made, reasonably priced and a straight fit.