At this time, I think this subject can be put to bed for the foreseeable future. I didn't really do a detailed recording and tweaking of the timing table but I did make changes based on some assumptions. In my experience, I have found GM's programming to be pretty well matched to the mechanical attributes of the engine. Sure, it is possible to make gains around the edges, especially if other things have been changed physically. With that in mind, I initially added ten degrees of timing to the entire table just to see if it felt better, and it did in many ways. After some testing it proved to be too much but I reasoned the overall progression had been scienced out pretty well by GM. I then took two degrees out overall, leaving an eight degree advance from stock. I then removed another six degrees from the area around idle speed and load. This appears to be a happy combination. Cold start also has improved on its own as the ECM learned what it wants. In any case, the engine feels nice and responsive, and full throttle while rolling in second gear to the shift shows a handful of knock counts right near the shift point. The S/C makes a very satisfying scream as well. I will monitor this on occasion, but it seems pretty happy.
Indirectly related to this thread, I neglected to reinstall a couple of spacer washers under the passengers end of the strut brace when I reassembled after the engine change. This causes intermittent contact of the large Hydac accumulator which is audible in the car. Perhaps a blessing in disguise as it seems the pump runs more often than it should. The brakes work fine and no warning lights. Today I had the chance to check the pressures and volume with my test rig. I found that it took 24 full peddle strokes to finally get a hard pedal, a testament to the large capacity of the Hydac. With the key on the pump operates in the textbook pressure range, 2600 psi off and 2000psi to restart. I also found my high pressure needle valve on the return to reservoir leaks by a bit, but that also seems to be a blessing?? I generally crack the valve just a bit and let the system build pressure while returning a bit to the reservoir so it continuously cycles. It appeared I had to leave the valve in what felt like a closed position to get the pump to build pressure but it was in fact letting some fluid through at all times, so all is well there. What did seem to come from this was the pump seems to build pressure more quickly and can tolerate more leak by to the reservoir after the circulation of fluid from pump to reservoir, almost like it was a bleeding operation. No empirical data to support that, but that was it appeared to be? Testing of the residual gas charge in the accumulator indicates ~900 psi remains after about six years of use. I am going to monitor for a while before I reinstall the spacer washers.