1964 Valiant Tallest Front 15" Tire

Not sure why you are trying to dog that little /6 motor, but adding all this rubber is going to do it. Plus trying to steer a 235 with manual steering ? Get out your Popeye arms.

My suggestion ? Let that slant run with a 205 or 215 tire.
I run 215 70 14 tires on Mopar 14" x 5.5" steelies.
Much lighter than the other tires mentioned with 15" wheels.
Your slant motor in Vixen will be thanking you.

.02 Drive through buddy. :)