With 111 cc heads, you will not get close to 9:1, I doubt you can even get 8.5:1 using the thinnest head gaskets and true flat tops.
These are the only decent bolt on Pontiac heads that work well on a 455,
#64 1970 455 87cc,
#96 1971 400 96cc,
#7K3 1972 400 96cc,
#6X-4 1977-79 400 84-86cc,
The 1971 HO wasn't much of a engine. It had a terrible cam in it, the compression was to low, and the exhaust ports were way to big. Other then the heads, the engine was just a stock 455, in fact, every 455 made other then the super duty, used the same crankshaft, rods, and block. The last castings in '76 were weaker ( lighter ), but pretty much the same engine. Pontiac varied the compression with heads, from 10:1 down to 7.6:1.
Call Jim Butler,
http://butlerperformance.com , and ask about a dome piston. You will need to buy pistons anyway, so why not spend a little more and get the compression where you want it. Explain the engine combination, altitude, and fuel availability, and see what they suggest.
If you go with a 389 or 400 cubic inch engine, you can easily get 9.5 to 9.75 :1 compression and still be with in the limits of the Tri-power. You will be amazed how well the combination will run. Dad's 1965 Catalina wagon had a 330 hp 389 tri-power engine which he won stock eliminator with 1965, and still drove it to work everyday. Hauling seven of us little snot's, it could get 14 mpg. The big cars had vacuum controlled outer carbs and the small center carb, GTO's got the mechanical linkage.
Any 72cc head from any 4 barrel Pontiac will work pretty good, they all flow about 210 cfm in stock form, even your round ports. Just look for any head with screw in rocker studs, they all had the 2.11" intake and 1.77" exhaust valves. Some heads used smaller exhaust valves and press in studs, but can be machined for performance applications. The smaller engine will save on buying a crank, as most guys throw away stock cranks and replace them with the stroker kits.
The older closed chamber heads with the 1.92" int and 1.66 exh valves had 68cc chambers and work decent ( pre 1967 ). In your application where rpm is not a factor, these old heads will work just fine and still give decent performance. The '65 - '66 GTO's ran really good with 389's and the same heads were used on the big 421 tri-power Grand Prix's. At the drag strip, dad's 389 wagon could beat the 421 cars due to wheel spin. The wagon wold hook and go, the 421s spun the tires and couldn't make up the time by the end of the track. The 389 was a real runner.
Joe
