The 305 heads with the 58CC combustion chambers can be opened up for 1.84/1.6 valves, and with a little pocket porting, you'll have good breathing and reasonable compression. There's a machine shop down in Florida that's selling heads set up that way, with guide plates and all the go-fast goodies for a very reasonable price. I don't remember the name of the place, but they advertise on E Pay all the time. The 283/327 "Power Pack" head with the pyramid-shaped casting identifier on the end of the head also has a 58CC chamber, but the valves are smaller.
Jerry

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