i had used a nv3500 in mine and everything has worked great so far. used the auto crossmember, had to move it back but worked great. found a master clutch cylinder that has boltable ear tabs not the plastic snap one. have good clutch action and it engages about half pedal. hooked the mc upto the original clutch setup so no have mods. the only think was i had to get a shortened driveshaft made. which was like $200 for new everything from scratch, so not bad but one point to know going into it. here is a couple pics but can check them all out at my build thread
http://67-72chevytrucks.com/vboard/s...d.php?t=359200
you can see in the one picture that i used a peice of stock to take up the slack between the mc and clutch pedal difference.