Why not go with the NV4500 and use the original hydro bellhousing? I can set you up with the hydro clutch master cylinder conversion.
Some say that there could be clearance issues between the slave and front driveshaft, but I don't think it will be a problem. You might find a little helpful info in this thread.
http://www.67-72chevytrucks.com/vboa...d.php?t=558135
Then you just need a round pattern NP205