Your combo and mine are very close. People here used to give me a hard time for running a 3.73 gear. Once my short times got into the 1.3s, the critics seem to vanish.
A 3.73 gear by itself WILL slow most cars. HOWEVER, If you run a taller tire (28"), your final ratio is only about 10% lower than stock. The 3.73 gear will also allow you to run a slightly tighter converter, as the rpms will be climbing quicker, spooling the turbo along with it. This tighter converter will have less slippage at the big end of the track and get much of the rpm back that you lost with the lower gear. I also have an old Art Carr 9" non lock up converter from the 90s. I tried one of his newer ones a few years ago and wasn't that impressed. My converter is at 2800 rpms at 0 vacuum and has about 4% slippage on the big end. Best to have ported heads/cam and good valve springs to make use of the extra rpm you'll have at the end of the track. At 124 mph I think I'm at about 6200 rpms. Here's my combo.
http://www.turbobuick.com/forums/threads/my-87-gn-cruise-air-10-55-et-21-mpg.370097/
3.73 gears got popular with these cars in the 90s. Before alky injection, people needed a big, slow spooling turbo to make power, and a loose converter to try and spool it. Most converters weren't nearly as efficient as today's are. The 3.73 gear was a way of keeping things streetable, without going to any looser of a converter than you had to.
Happy spooling.
Mike Barnard
