[chiphead]

I broke out the calculator on that distributor setup. Since the dist turns half as fast as the crank, you double the degrees and RPM stated on the Sun sheet to calculate the timing at the crankshaft.

I get
16 degrees advance at 2000 RPM
20 degrees at 2600
24 degrees at 3400

Assuming the typical Pontiac engine wants total timing to be 36 degrees (which includes base timing) you subtract 36 from the 24 degrees of dist advance to get 12 degrees at idle. So the base timing would have to be set at 12 degrees BTDC to give 36 degrees at 3400 RPM. Base timing (which you set) plus dist advance curve (calculated above) gives the total timing the piston will see at a given RPM.

The total timing at those RPMs with 12* base would be
28* at 2000 RPM
32 at 2600 RPM
36* at 3400 RPM

So take a timing light and verify you have 12* of base timing. This is your starting point for tuning. What's interesting to me is that there is a decent amount of timing from 2000-2600 RPM, but it takes another 800 RPM for the curve to come all in. I assume they did this to provide a safe tuning window that won't rattle the bearings due to too much timing too early.

At low 9s static compression, on 93 octane gas, I would think it safe to quicken the second half of that curve. Basically have all the timing in at 2900-3000 may increase some power in that range. Maybe 15-30 HP depending on what the engine likes.

But that's not going to provide a world of difference unless the actual timing is vastly different from what I estimated above. For comparison, my 400 motors tend to like 14-16* of base timing and 34-36* at 3200. So shoot the timing with a light and report back.

Cranking compression is a decent estimator of how an engine will behave, if engine size, compression and camshaft is known. Manifold vacuum at idle will help tell if an engine is tuned properly, at least at idle. You put the two together to estimate an engine's power potential and if the tune is in the ballpark.

Edit- I just saw that your cranking PSI is in the 160s. That's not bad. My 400 with 2802 and 9.7:1 compression pumps 165 and it's no slouch. I'd look at ignition timing and carb settings first. How about shift points? How long does the 2004R hold 1st gear at heavy throttle?

I do think that the biggest gains would be heads. Its not just airflow. Going from 9.3 to 10.3 compression is going to pick up power everywhere. The power production above 4500 is going to benefit from headers and 3" exhaust, but down low, cylinder pressure rules.