Light duty pick-ups and vans came with A833's most were the OD variant that would not be the best choice for a drag vehicle but are great on the street.
The long tail shaft A833 from a van or pick-up (or e, b, c-body) can be used in an A-body, I have one in my 68 Barracuda. The front mount on these trannies is to far forward for an a-body (the mounting bosses wind up under the torsion bar cross member, I had to cut one off to make clearance but denting the cross memeber is another option). The rear boss is about 9" behind where the A-body mount is positioned, I used 1/2" alumium plate to make an adapter to move the shifter forward and another spacer about 1 1/4" to put between the shifter adapter and the 1/2" plate to move the shifter over to the drivers side so it would come through the floor in the stock location. You will need to get the drive shaft shortened. Everything else just bolts up.
If you happen to have a crank that is not drilled or not drilled to the finish size you have options. If the crank is not drilled at all you can cut about 1" off the input shaft of the tranny and use a late model Ram/Dakota pilot bearing that fits the torque converter register. This bearing is a roller bearing verse the bushing that was stock in these cars. If you crank is drilled but not to the finish size NAPA has a special thin wall pilot bushing that fits this size hole.
As far as the hump extension for the floor you can cut one from a doner car or get one new from Sherman. 67_Cuda when I installed mine (removed from a doner) there was not a question about the positioning of it. There was only one place that it followed the floor contours correctly (there was maybe a 1/4" wiggle room). I traced the hump on the floor and cut the floor 1/2" inside the trace marks.