can anyone help me get an extra 200 hp out of my stock 340 what parts do i need to change or what never can get anyone that i talk to with a straight

well, what's the current set up and how much power is that making? how has that power been measured or verified?

the answer is probably a stroker kit along with some other bits, depending on what you have.

stock they were rated at 275hp (with actual accounts of near 300), which would put you into the damn near 500hp arena. not impossible to make on a "stock" motor, but much easier and cheaper to do with a stroker.