I put RT emulators & shortened the OEM fork springs for my son's. Used 10w oil @ 100mm form top, collapsed w/o fork spings in. Was on the stiff side for his 75-lb body but real good for me, way much better than the stock setup - no more wet-noodle front end!
A fork seal recently began leaking, so after changing seals I used 5 wt oil, replaced the short emulator spring with the lighter one, & it's more suited for him.
We do off road only, no MX, but can certainly do the latter if need be now; totally oout of the question before, when stock. Well worth the $ if you plan on keeping it for a while. If not & you wantto keep it on the cheaper side, cut the stock springs 1" & install PVC spacers of the same length.
U R taking no chance by sending the engine to Eric for work. His personal service, knowledge, & attention, I'm told, is not even in the same league as the big shops; I'd leave mine stock before sending anything to the latter (PC & FMF). My RMX barrel is going to him later this summer.