As with any engine, zero deck height and optimized piston to head distance is important for detonation control and that certainly applies to the Pontiac. I'd recommend strongly against having the pistons down the hole, machining off the entire piston head, and/or using head gaskets that are more than .045" thick, as anything over .060" clearance between the head and the piston increases detonation sensitivity rapidly. Combustion efficiency will also suffer. If a dish must be machined in the piston, match the dish to the chamber shape as Mr. P-Body said; the extra cost shouldn't be that much.

Pontiac combustion chambers are fully machined so the CR is more accurate and consistent than SBCs and only need the sharp edges rolled. Pontiac heads do have a quirk that makes them more sensitive to detonation; they have the spark plug closer to the intake valve, which means that the flame front moves from that side to the exhaust side, leaving the last part of the mixture to be burnt (end gases)right beside the exhaust valve. The exhaust valve raises the temp of the end gases, increasing the detonation sensitivity, and the hotter the exhaust valve gets the more it increases the likelyhood of detonation.

To help with that, make sure the exhaust system is as free flowing as possible. That will reduce the exhaust duration needed on the cam and will keep the exhaust valve cooler by keeping it on the seat longer. Also, make sure the cooling system is working as designed; the separator plate behind the water pump needs to have the right clearance to pump the coolant properly and there are several threads about that.

I like to use a cam that has a fairly tight LSA (110-112) to bleed off a little more cylinder pressure at the lower end while concentrating the mid and upper-range power. A wide LSA tends to take power from the middle and add it to the low and high rpm range. That has two consequences; it increases cylinder pressure at the low rpm, which we're actually trying to reduce, and requires the engine to rev higher to make up for the drop in mid-range power. Pontiacs are not high revvers so using a cam with an LSA of more than 112 spreads the power range out too much and reduces the famous Pontiac mid-range torque without adding horsepower. The Pontiac factory grinds usually had more than a 112 degree LSA and were great cams at the time; a newer grind will work better IMHO.

The higher the static compression ratio, the more valve timing overlap is needed to reduce the cranking pressure and keep detonation under control, and a smaller LSA increases overlap, as does increasing the cam duration. Matching the cam selection to the rest of the engine is important.

Tuning is also important: an overly rich or lean mixture will elevate the exhaust valve temp, again raising its temp and increasing detonation sensitivity, as will ignition timing that is too far advanced or retarded. Use vacuum advance to keep the engine clean on light throttle and of course to increase fuel economy.

Proper selection and matching of parts will result in an engine that makes very good power on pump gas, keeps the engine temp down and gets decent fuel economy.