You may not need a complete rebuild but you might need all new seals and so you'd have the labor to take it all apart, install new seals and reassemble. If you're rebuild guy is good, he might be able to reuse some of the seals, not sure, but they may be assemble-once-then-discard type items.
Either way, new seals aren't too much money but the labor would be the killer. The seals on rotaries are the fragile parts. When they go, you don't have many options and they can go if you get dirt in the engine, but I'm not sure about it getting in through dirty fuel. Was the engine ever run with the air filter off or ram air or anything like that? Dirt can get in that way pretty easily if you're not careful. I got only one racing season on a 13B when I tried a ram air setup and think I got dirt in through the air filter (at least that what my engine builder said). Back in the 90s, there was a guy Carol Ashley, he went by the name A.J., who ran a shop on Long Island called Father & Sons Auto where he prepped a bunch of 2nd gen RX7s for racing. I'm not sure if this is the same shop as the used car dealership with that name but it could be. You might want to call them and ask for AJ and, if he's there, find out if he still works on RX7s. Otherwise, I don't know anyone else on LI but I sold my rotary several years ago.