Wiseco, JE, Toda, TRD alldo forged pistons for our engine, all have oversized options too. Pistons don't affect stroke though you'll need a new crank if you want to go stroker.
Trd and Toda do heavy valve springs or you could double up factory.
Why do you need oversized valves? The manual head valves are already massive.
Nick the site trader does a great deal on forged pistons and rods, pretty much the best price you're going to get. Think they're cp pistons and eagle rods. Which you'll be able to state oversized or not.