Did a search: 3/4"-1" of slip yoke travel before bottoming seems to be the most popular answer. Hope this helps.
Don't really know how the transmission 'knows' what gears are behind it, as long as the gear ratios in the transmission are the same the shift points should be the same. That being said, on paper it looks good,but in real practice its a different story, the change in shift point might be caused by there being less actual load on the drive train due to the mechanical advantage of the lower gears,and causing slightly less slippage in the converter, dropping the relative speed of the engine compared to the tail shaft. The shift points are then slightly lower.
I ran a stock 455 Stg 1 in a 4 door Electra for a couple of years (about the same power to weight ratio as you have). I originally used 3.42 gears with a 2500 stall converter with a GN "BR" code overdrive trans and 235X75X15 (28.5") tall tires. I tried a set of 4.10's, it launched better and ran faster 60' times but only picked up a tenth or two in the quarter and actually slowed down a couple of mph. The 4.10's were more fun around town but did nothing in the 1/4. I eventually went to an 1800 stall converter because I hated the lurching when cruising without the lock up on of the 2500. Go with 3.73's max. Mikey
We ran 4.78 factory 8.2 gears in our first GSX stage 1 on the street. Ridiculous is best word to describe the experience.
There was a guy at the local track that got a 4dr 71 Skylark for free from his grandmother. It had 350 2 barrel and 2.56. It ran 16.40s with welded spider gears and sticky tires. He found a used set of 5.00 8.5 gears (yes 5.00) and slapped them in. Ran 15.30s then.......he used to loan it to people who broke their drag cars. Ran for a long time.......until rust chunks started falling off when it left the starting line and it was junked. Imagine finding that in the boneyard and thinking it has 2.56 gears!!!???ou:
