Well i would just get new pistons since your gonna need a bore and hone joby if you have the cash pull the bottom end out too get a 4mil true and welded crank in stock stroke and yess you can port your cylinders as they sit
Its not like hes gonna be at 340 or 350 with no port work i wouldnt think so a 300 to a 310 should be with 27.5 even 30 is fine im and again im 1200ft asl...
What i have is a set of white front and rear plastics 125+shipping
Set of psi racing pipes (look rough) no major dents in them 80.00+shipping
Rear trakker paddles on gold yam wheels
100+shipping
When you squirt that TINY bit in the cylinders and put the plugs in kick it over quick and its gonna gonna rev high for a few secs if not with in 5 sec shut it down and check everything
Mines not ported but it runs great i just do the regular maintenance on it clean it and before i jus rebuilt the top end i had like a season and half on it