Ok, so the brake conversion makes a big difference. That’s a 73+ disk set up drilled for SBP, so it widens the track width.
If you want a 15x7 up front, you should use a 4.25” backspace.
With the 4” backspace on a 15x7 you could run a 205/65/15. A 215 would be really close to the fenders. That would be as wide as you could go, and you’d probably want to keep the height below 26”.