I use the clutch disc from an 83-84 2.8L v6 Firebird. Doesn't require any modification to the clutch disc. I've outlined the process in detail on page 5 of my Webshots "Shoebox" album. I've also used the RCF-4201. Both came from NAPA.
As for your gear ratios.....you're correct.....the 4.03 is going to have you short shifting but the .86/3.90 would have you turning about 2200 @60 mph with plenty of throttle/rpms left in reserve and the ability to drop down towards 45 mph without a downshift. The .72 T5 isn't that much of an improvement in regard to the short 1st gear.
As for the driveshaft.....I've found that the driveshaft from a S10 T5 shortbed pickup can be used without modification by moving the spring pad 5/8" to the rear...which centers the rear wheels in the bed wheel well. Hope this helps.
Dave
