I read an easy way to guesstimate streetable HP potential from a V8. Multiply the displacement times 1.2, and that'll give a rough estimate of max streetable HP from a given engine. For example, if you multiply a 327 times 1.2, you get 360 HP. That means you can get about 360 HP out of a 327 and still get decent street manners. Try for more power than that, and the engine will idle poorly and require race fuel due to a hot cam and high compression. Thats when it becomes a race engine.
A general rule of thumb is that you're doing well to get one HP per cubic inch. 1.2 Hp/cu-in means you got the combo perfect.
Shoot for a compression ratio of 9.5:1, a cam with around 220 degrees duration and .475" lift, a dual-plane manifold, a 650 vacuum secondary carb, HEI ignition, mild porting of heads, block zero-decked. Bottom end balanced and blueprinted to factory clearances. Use TRW flattops and a good set of rods. Find a set of heads with 60 CC combustion chambers, large valves and screw-in studs.
These parts are just a suggestion, so do your own research to decide what RPM range you want. You should be able to get 300 HP with an RPM range of 1700-6000 or so.
You need to figure out what year 327 you have. The size of the crank journals changed in 67 or 68, so there is a "small journal" 327 with mains the same size as a 283 and a "large journal" 327 with mains the same size as a 350. I don't think the crank & rods from a "small" 327 will fit in a "large" 327 and vice-versa. This is where more research is needed for proper parts selection.
good luck & let us know!
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