On my 48 DeSoto, I used original latches, and lock cylinders. I thought the lock cylinders were cool with the little twist flaps to cover where you insert the key.
To prevent lock out, I leave one of the vents unlocked. Probably not the smarted thing, but it works for me, and all was simple. I believe in 'simple.
See my signature
But, I sure do envy/admire y'all's imaginations and talents. Us old ignorant country boys gotta keep it inexpensive and simple.

Jack