Before this gets too carried away, statements have to define and limit the engine combinations that we are talking about. It does little to base your opinion on the latest, greatest, and most expensive after-market blocks and heads. By the time you have altered every dimension of the old small block, can you really still call it a true representation of a Chevy engine? We can talk about exotic engines made of unobtanium, engines made up of expensive parts, or what was delivered from the factory back in the day.
1. Unobtanium goes to Chevy - Years of multiple after-market suppliers have introduced some truly impressive speed parts. If your wallet is big enough, Chevy wins. But again, is it a really a Chevy engine at this point when nothing will interchange with the original engine?
2. Just really expensive parts to modify your engine - Very close call today. Pontiac after-market suppliers are finally starting to appear and this segment is hard to call with Pontiac finally making up some ground. This is going to be an interesting arena in the next few years for all engine makes. Last Pontiac performance engine stopped with the 1974 model year, and there were very few produced with the gas crisis and insurance companies wrecking havoc. Pontiac people have had to work with parts that were made at least 36 years ago and sometimes 46 years ago while the Chevy engines continued to be produced and refined by Chevrolet and after-market suppliers. Old Pontiac technology held up remarkably well without any refinement from manufacturer or supplier input, and this old stuff still remains competitive in this mid-range competition. As for today, have you researched the CV1 Pontiac head? Pontiac Tiger heads? The new generation RAV aluminum head that just hit production? There are two aftermarket Pontiac block suppliers doing both cast iron and aluminum that can easily live at 535ci on the street, larger for strip only. Cool times ahead for everyone, and finally Pontiac is included.
3. Stock off the showroom floor - Pontiac won hands down, and it was superior to either the small or big block available engines factory installed in Chevrolet's. The Pontiac's were drivable anywhere which wasn't always the case with other higher compression engines. It was a very rare occasion for a stock Pontiac to loose a street race against another stock car. I had a '63 Chevy SS Impala with the 327 (in 1963) that would chew up most cars on the road (including 409's that always seemed to load up and not clean out in street driving), but not the Pontiac's. In '67 I traded in my SS, and factory ordered my GTO that I still have today. I was 19 when I took delivery and did plenty of "testing" out on the street against other brands. So my results are first-hand.
Pontiac cylinder head combustion chambers are fully machined. There is no equalizing chamber sizes like on a cast Chevy chamber, and all Pontiac chambers are right on the money. There also are no casting irregularities that can screw up flame travel. Chevy after-market finally introduced the air-gap manifold bragging about the horsepower increase, but Pontiac always used a separate valley cover. Finally, the Pontiac torque range was brutal. What wins races is the total power available under the curve, and there is no contest here. Dyno results for the Pontiac engine produce a flat line for torque across the curve. Now in drag racing on the track, you can make up for the small block's output by gearing way down, ridiculously loosening up the converter, and screaming it to the stratosphere -- but this produces an engine that is miserable to drive down to the local store, never mind across town or a real road trip.
Anyway, that's my story and I'm sticking to it.