I can't say what plug to use,your heads may need longer reach or peanut plugs...just get a mid range alky plug in the style required..when you pull your plugs-make sure the electrodes aren't smashed..it's no uncommon to have to index plugs on racing motors so they don't hit the pistons..buy a leakdown tester and mag buzz box from Speedway Motors...most timing lights don't work well timing mags..easier to buzz the mag in...you set the barrel valve with a leak down tester....IF you have the right size fuel pump for your motors needs -you shouldn't need a s.valve.....you may need a high speed but you should wait till you see if your motor 8 stokes under full throttle on the straight a-ways,if that happens add a return line with a high speed set to open at 58 lbs/about a 65 pill