I have a homemade side mount spare bracket on my '53 3600. I'm running 235/85 R16s and there is sufficient room, so I'm pretty confident you'll be able to make it work. My bracket consists of angle iron which I welded and drilled for 3 wheel studs. It is welded to the stake pockets. I can take the spare off and get some pics for you if you'd like. I've had it this way for 20+ years and I like it a lot. Spare is convenient and not taking up space in the bed.
I'd be interested in seeing your set up. I've been thinking of making one for my 3600.
