If your object is just to get it running why are you stressing about how the Radiator mounts? Place any radiator you want in the location and wrap some baling wire through the mounting holes in both the radiator and the bracket to hold it in place while you do your thing. You can then concentrate on finding the proper radiator later after it's running/stopping to suit you. Just an idea.
That is a good point, but I was trying my best to find what would actually fit like it should if I could find it. I do have some old random radiators laying around but was worried about them fitting in there and me trying to tie it up without hitting the fan since those are mostly big and for tractors. I did think of that though.
If I went to a junk yard, what would you recommend getting that should fit in there and work ok if I tied it up with wire?
