14's for the small bolt pattern? '65 Valiant

I have a 64 and a 65 with SBP 14" wheels on both. Nicest set is Cragars I got via FABO. I got a set of alum slotted wheels locally for $100. The rears are wider which gives a bad boy look. The convertible came with spoke wheels that look fantastic. Don't know the vintage.

My point is you can get SBP affordably if you are patient. Indeed, with so many people switching to BBP, there may even be a surplus of SBP wheels. If you do go BBP, most change the rear end to BBP so they don't have to carry 2 spares. Sometimes desireable to get a tough rear for drag racing, but not needed for your slant. My thought is that so many people are ditching their 7.25" rear ends, I can get those almost free and have spares for if/when my rear ends fails.

You would get faster acceleration with 13" wheels, but they look a bit dumpy, especially on early A's. As you say, 14" will lower the engine speed for better mileage on the highway and probably a smoother ride. Of course you can get different profile height tires in either so the O.D. of the wheel could be almost the same. Another advantage of 14" wheels is that some disk brake conversions can fit under those.