You can do some 12"+ extensions if you want, they will help the bottom end some NA and the cost is minimal, as are the gains. However, if you are going to use N20 say a 150 hit frequently and hit it off the line as I did (only way to do it in my book) the torque increase on the hit will be huge negating the use of a T-brake as well somewhat, but for an extra $500 you may as well get it, I would change the converter as well to something in the 3500 range, and up the cam to something like this if you wanna stay hyd.
20-229-4 - Xtreme Hi-lift Hydraulic Flat Tappet Camshafts...or
20-228-4 - Xtreme Hi-lift Hydraulic Flat Tappet Camshafts
but these comp fast rate cams don't help much with top end rpm as the lifters don't cope too well with them....Hughes hyd. cams are easier.
After running that old .590 solid DC cam I would never go hyd. in any performance type application where rpms are going to exceed 6000.
Or you could change the gears to something like 4.10>30's which should get you to the stripe ok and keep it pulling@5500rpm with the NA power you have with that mild 274H cam but that may slow you a touch in the 60's...the problem is with a 125/150 shot you'll be turning just over 6000 (4.30's) and with a hyd. it may give issues in the valvetrain......never easy is it. Personally I would go to a solid ft cam, of course all dependent on funds etc....how far do you want to take things as to how fast do you want to go is always the question....you could go 10's NA with a pair of those new TF190 heads, or anything with at least 280cfm flow+ a cam/inlet/carb/hdrs/converter to match if you have the $$$$$.
