It shouldn't be too hard to find a later flatmotor that will bolt in. Any pre 8BA motor will be an easy bolt in. Ford designed them to be so. Any 59A motor will fit directly to the gearbox, the front mounts are accommodated with a simple adaptor (I made my own) and the only other thing that needs adaption is the top hoses, which are easily done with some bends and a couple of lengths of tubing.
I put an English Ford Pilot 21stud in my 33, and made the adaptions, I am now preparing a 59A for it, which will be a direct bolt in.
If originality is important to you, You could then either rebuild your original motor, build up a 36LB motor for it or any other combo that fits the original look better and drop that back in at a later date, undoing the adaptions previously made.
I have pics of the adaptions if you would find them helpful, they are in my "three month 33 survivor" thread.
http://www.fordbarn.com/forum/showthread.php?t=77133
Mart.