Our basic timing is 40 degrees initial, and it comes down by a little under 1 degree / psi so that at imaginary 26 psi there should be 20 degrees.
Our gear ratio is 4.10, tires are 18.5/33 ET Streets and against the 7500 rpm limiter through the traps at 175 mph. We tried and actually succeeded to lower the converter stall about 500 rpm with oil change; went to SAE 80 wt oil in the trans. Itäs similar to John Deere Hy Gard, but thick and it worked. Of course we couldn't get everything out of the trans, so it's propably about 1/3 ATF and 1/3 SAE 80. Even with teh tightened converter we still use the same fluid, ATF only for colour. The trans internals looked good the last time it was down.