Nathan, that "rebuild" might be good for many miles. It does not sound like it was what would be called a full rebuild, unless the cylinders were bored (and/or, honed and measured; and, the crankshaft was ground or measured; and, unless the head had the valves and valve-seats ground/dressed.
Other people here are experts and they have already provided better and clearer responses. They will probably/hopefully comment on your "full rebuild".
Have you checked the compression and checked the oil pressure on a warmed up engine.
Nonetheless, check out and use the engine. Maintain it carefully. These engines are robust - it could easily last you many years and many 1000s of miles.
