the difference heads small block

With the capabilities and pricing of the aftermarket heads now available I can't see using factory heads in anything other than stock form. Spending money for anything beyond a valve grind and new guides is a waste. The only exception being if you can do the port work yourself, in which case you can save yourself some money still.

I had a set of 308 heads totally reworked for my 340 because the pistons I used were proud of the deck on my early 340 and I needed an open chamber head for reasonable compression numbers. 2.02/1.60 valves, chamber work, new valves, spring guides, etc., and a stage II port. After everything they flowed 254 cfm @ .500". But I'd also spent over $2k.

With the aftermarket heads out there now you could have brand new heads that flow that well or better for the same, or even less, money depending on your choices. I set the 318 for my dart up for zero deck and bought a set of RHS heads for less than I put into the 308's. The capabilities aren't identical, but for my application they're more than enough.