1967 Barracuda rear tire/rim help needed

I'm running 245/60-14 on the back of mine. I have been looking at it, and with my backspacing I'm pretty well centered between the leaf spring and the lip of the wheel well. I could probably squeeze a 255 tire in there but it would be a little tight. Yours should be the same width tire, just a little taller with the 15" rim. I am running stock rallye wheels, and I can't say for sure what the width and backspacing are on those.

Here's a couple pictures:

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