Rainman,
Gear multiplication you get w/ OD trans. helps SBC's, but IMO a good big bore poncho V-8 doesn't really need it- any poncho w/ a long stroker crank like a 4, 4.21, or 4.25 will make so much more torque off of the line the added gear multiplication only hurts you at launch and goes up in smoke if you don't have wide slicks or are running regular street tires. This is why a well-built 455 w/ a TH-400, shift kit and a decent 2500-3000 rpm stall, and a 3.08 posi can propel any mid-sized Pontiac into the low 12's, even w/ a suspension optimized for the street. The gearing doesn't overpower the tires at launch, and lets you put the power down and accelerate. This combo will still smoke the tires at launch, but once it hooks up the midrange power is tremendous.
I used to have 2.41's, which made launches lazy at best, but would let my 400 peg the 160 mph speedo. The 3.08's did limit my top end to the 140's w/ the 400, but with the built 455 I had before there was more than enough torque to bury the speedo needle again. 2.56's w/ a stout TH-350 and a 400+ hp 400/455 stroker will no doubt propel your TA into the low-mid 13's easy, as well as give you good top end.
Geno
