Same as above post, they should work. The only suggestion I have is about the front cross-member just under the front of the tranny. Not sure if it's the same on yours as mine but here goes. On standard drive trannies the front member is most of the time rivited in. You will need to grind out the rivits so you can remove that crossmember to get the C-6 in. On 67-72's you cannot get a C-6 into the tunnle without removing that crossmember.
On the drive shaft, if your does'nt fit due to length hit the junk yards with a tape measure. Alot of those trucks came with C-6's in them so finding the right length should'nt be a problem. Are you gonna use a floor shifter or are you gonna change out your column. If your colum is for power-steering already it may be worth alittle on Ebay. power-steering automatic columns are also easy to find. Yours with the shifter delete is harder to come by. Hope I got everything right.
Clint