My advice is to keep the 351C 2V heads but get them pocket ported and gasket matched. Use an Edelbrock performer or Performer RPM (possibly a Weiand Stealth) intake. A Holley or Demon 750 with Vacuum secondaries should work well for a 351C.
1 5/8" primary long tube headers (even Tri-Y's) work well to 6000 RPM. I use a "muffler shop" custom 2 1/2" exhaust with 3 chamber Flowmasters. The CC 268 HE cam (as previously mentioned) is a good choice. Mine works well to 6000 RPM.
A good electronic ignition would round out the engine. There are lots of other little fine tuning things to do, but these are what I consider the main things.
Rev
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'66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi.
O.B.C. #2
'66 coupe
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