Achipmunk, not sure on your vehicles (37 and a 52). Mine is a 47. When in question add some more steel. The CE trans support goes where the mount for the 700R falls.
Scotricker, the engine adds a lot of strength in itself. If you plate the frame in the spring mount areas you will be fine. The trans cross brace also adds rigidity.
The frames were designed to flex back then anyhow. I do not think you will have any problems. Remember, the axle is also a cross member. Good luck with your build and just use common sense.
Like you said; it's just a driver! 😎
