The RX7 caliper will fit under 13" wheel. The RX7 276 mm disc rotor won't fit with 13" wheel.

For example, fit the 4-pot caliper to the 212 mm 120Y rotor. It will require a different kind of mounting to get the caliper fitted that close to the spindle, perhaps a ring mount. Brake pad spacers can be used with thinner rotors.

You can fit the RX7 caliper with 252 mm rotor under some 13" wheels (but not all 13" wheels). 252 rotor comes with 280ZX. Or with 250 mm rotor from S13. You can notch the caliper to get it that close to the spindle, 4-pot caliper can be ground a long way to get it close.