We have not had the best luck with the NV 3500 (or T5) trans in anything with a lot of torque and/or big rubber. Fine for cruising or showing but iffy if hammered. As far as clutch actuation is concerned the factory set up from the 60-62 Chevy pickup hydraulic system can be used or from early 90's Chevy pickups that came with the NV 3500. We used the McCloed after market hydraulic TO bearing and plumbed it in. Concerning overdrive transmissions one can still pickup the old BW 3sp OD unit at swap meets for $250-$500 and it is as strong as the T5 or 3500 and gives a final gear of 3.05 with a 4.56 or 2.88 with the 4.11. Just make sure the solenoid is good before purchase. I came to Texas 60 years ago from Minnesota and can relate to wintertime difficulties in working on old rides. First winter in Texas found out it's WAY easier to shovel sunshine.
