you are not going to get it in there otherwise unless you manipulate the floorboards severely, you will then need to install a rear trans crossmember. if you could find a powerglide rear crossmember from those years it would make it handy for you, there are other options though.
http://www.persh.org/pickup/700R4.htmron
you may also have to do a little work on that seem that comes down under the firewall -on top of the bellhousing area for clearance. If all of your cab mounts are in good shape(not collapsed or any rust problems in that area) you may get away with not having to do that little modification' one thing always leads to another
