Compression is only 14.1 on the big bore kit, its their factory kit that uses 14.8 to 1 compression. Athena suggests using 96 octane but, I've been fine on 93. Factory manual says 95 octane stock and alot of people run 91 or or 92, so eh. I'm not saying its the best or you should do it, just saying its worked for me, pump gas is so much easier.
As far as port timing I don't know, the power valves themselves are new, but use all the guts from your stock ones.
I had my bottom end rebuilt and put in Vforce3 reeds same time I installed my big bore kit, but the power was noticeably better pretty much everywhere, especially after getting it jetted right.
So far I would recomend the kit. If I would have known about the ama rule change and the making of the 125 class at the time, I probably would not have done it though...