Rust...
On calipers, on discs, on anything metal. Internal engine issues like frozen apex seals, rust on all the suspension bits, and on and on. And on the engine, if it's frozen, it's basically a crap shoot as to whether it's going to last after a few trips to 8K rpm.
The thing about 1st gen RX-7s is that you can buy a full setup from a guy with proven lap times and spares and such for so little money, and be up and running right NOW. No welding in door bars to cages that weren't designed for that (and that can be a major PITA if the front and rear hoops are up against the walls, ) and so forth.
This is sort of a "build or buy" question. Sit down with a pencil and paper, or an excel spreadsheet, and take some known examples of cars that are for sale, and determine what this car will need to match what you can buy already built and proven.
The list could be long...a built up carb, EGT guages, oil cooler set up, pressure guages, belts, window net, rear gear, wheels, tires, a good shifting transmission, some form of lap timing or data aq system, upgraded radiator, header and exhaust system, rebuilt brakes all around with a proportioning valve and racing pads, a possible fuel cell (the stock tank is likely rusty and new ones or good used ones can be hard to come by cheaply), good wheel and axle bearings all around, a good driveshaft (big money, actually), a modified rear suspension, and modified front struts, camber plates, etc., ad of course, a quality cage.
It might be better to find some extra money via overtime or a second job than it would be to think you can do it all with sweat equity.
If it's not very complete, it would need to be close to free to make it worth it.....do some math before diving in!
