I'm leery about untitled cars to begin with, but the VIN being held down by 4 different screws? I'd say no way. I looked at a '66 mustang with a rebuilt plate on the door sill. The insurance company said they wouldn't insure it, and since there was no title, I was not about to take any chances of wasting money on it. If it doesn't feel right, trust your instincts.
I just realized that I didn't really answer your question. I don't know where all VIN are on a Willys, unless one was stamped on the engine block.