This is a very, very easy conversion to do. My first one was back in the late 50s when I was 15 (yes 15) years old. I did it without a welder or torch of any kind----just common hand tools at the time.
The original real axle will work, front bolt in motor mounts used to be available from Honest Charley(probably available from someone now), the rear trans mounts can be fabricated from two pieces of 1/4" plate bent in a "Z" shape and bolted to the original center cross member. Several steering boxes are available---the easiest is the 56 Ford PU. The firewall does need to be notched for fuel pump clearance---but an electric pump could eliminate that need. The original radiator can cool the flathead but a good fan is needed. The front radius rods must be split but that can be accomplished easily. I even used the original gas tank. The little 100HP engine pushed my coupe pretty well---really well when I had the heads milled, twin 97s and a "Sportsman" cam.
Wished I still had the car---but we all have those regrets!