What tire size will work with a 15x8 front wheel?

Like this... these are 225 60 15s on 15 x 7 with 4.25 backspace. I would say you are better off with 4.5 backspace... and you will likely still have to tweak things to keep them from rubbing. This car has 1.14 torsion bars and shocks with a good bit of compression dampening and I can still get some rubbing at times.

View attachment 1715057560

I got 1.09 bars

But seems to me yours is pretty close to the fender and 8" rims would move it out 3/4 of an inch further that way since its only got a 1/4 inch more back space.