Heh, been wanting to laser-cut and assemble an all-metal cam for awhile. One of these days...
Also, been saying this for years, but what we really need in order to step up the power level on these is someone to machine up a con rod. Beyond that is to improve on the oiling system, which was once attempted by a racewinner known informally as Nashmoto, the fastest guy I know with a GXH50.
The original con rod isn't that great, and there is room to improve on both the durability of the piece and the compression of the engine here. I think a 1.5MM increase in distance between bore centers would put the engine close to 10:1, which in conjunction with the cam would really wake these engines up.