I agree with Dan, do a compression test first, if the compression goes up it is the rings, if compression drops it is the valve guides. I didn't recommend the stock heads on top of the 331 because, it would greatly benifit from a set of good flowing aftermarket heads, cast or aluminum, it really all depends on what you want to do with the car. I have seen 347's topped with ported and polished to the hill stockers and they run good but it all depends on how much money you want to invest in the stock heads. Do you plan on doing a lot of racing? Is a blower or N2O in the future? These are all things you should consider before tearing it all apart, plan as best you can. I thought I had every little thing covered and still ended up $1000.oo over budget, but it was what I wanted, A** Kicking, raw power
Rick
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My Ride Check Out My Site 91GT, Holley SysteMAX II Kit-Heads 2.02" x 1.60",Full MAC exhaust 1-5/8" Long tubes, 2-1/2" O.R H-Pipe, 2 1/2" cat back, 12" K&N Filter, RNH PERFORMANCE Ram Air, Ron Davis Radiator, Full Suspension,3:73's, Welds, Best on new motor-12.60 @ 108, no traction 1.98