Strange combination, from what I understand. The 60cc heads have relatively small valves (1.72 in., 1.5 ex). Most builders want the 2.02/1.60 combination. According to the casting number, 376450, these are from a 75-81 262/267/305, with 6 or 7 exhaust bolt holes. If you're building for umph, you should probably upgrade.
dude!howdy! you did'nt mention what your plans for the rest of your build are.the heads you have are fine if you are not doing anything to the rest of your motor.if you are going to build a new motor i suggest you read several mags [chevyhiperformance,superchevy,etc.]you can get great build articles online at no cost from most if not all of these mags.at some point you need to decide how much moola you are willing and able to put into the project[i hate money, it always comes down to that!]anyway,holler back,see ya!jimm by the way ,i did'nt mean to suggest that you could'nt achieve more uummmph by changing to heads that breathe better,i was just suggesting that once you open the can of worms you could do a lot better by modifying other components as well!jimm
Well, there is a LOT of stuff you can do to an engine yourself, including porting etc. if you want to take the time instead of the money route. Here's a good book to check out, Amazon.com has 'em: "HOw to build maximum performance chevy small blocks om a budget", by David Vizard, the ISBN# is 1884089348 if you want to try to get one from your local bookstore. The reason the hot rod magazines push product instead of how-to, is their advertisers are in the business of selling product. They can make more money selling you $800 worth of heads than they can selling you a $30 porting kit, right? Some of the builds in the books get so rediculouly expensive they are a joke. Especially for a street rod.