I agree in thinking that for only 300 you wouldnt need almost if not any exotic stuff, and could probably stay away from most of what I had listed. I was speaking more for the higher end of the hp goal that you mentioned (almost 400?). For craps and giggles though, here is a few link to the part I mentioned...
I have heard that the shaft is actually made by Jeff Bruce from New Zealand, you may be able to obtain it cheaper directly from him, I just dont know how to contact him.
I have heard JHB performance can/does do the 3rd spark plug per rotor and cermet coatings as well as thermal barrier coatings. I have also seen mixed reviews about them, I would personally give them a try though.
I have always been told/read/observed that ceramic apex seals will seal just as well as any others at high rpms, if not better. They also have reduced wear as mentioned.
I dont think that making 300whp would be much of a problem, but I do think that making 300whp with some kind of mid range power/torque would be more difficult.