What rear end gears for 904?

Gotta make up your mind what you want to do. In post #1 you said you were after "fun factor" and in post #10 you said you may not be happy with 3.91-4.10 down the interstate at 70. I can guarantee you won't be happy with low gears down the interstate but with that low stall converter you have you probably not going to be happy with 3.55's for butt kicking fun factor either. Changing the converter to 3500 stall may make as much difference as the 100 HP shot of nitrous and as Kim pointed out, unless the converter was made specifically to take NOS it'll probably balloon and take out the mains. I had a 360 built just about like yours and can tell you from experience that you need at least a 3:73 gears or it won't be that quick out of the hole. If you swap to a 4000 stall you could probably get away with 3:55 gears and it won't be a monster at 70 mph