I think with proper pct and time along with some test boosters at first when your done with your clomid etc, I think you can bring yourself back to where you are now before hand.. Dont expect anything less than an uphill battle after being on test for that long..
Im a TRT Lifer.. Occasionally I will come off for whatever reason.. and even though I run clomid alongside an anti e as well as cort blockers etc.. My test levels never get much past 300.. regardless of how long I pct..
TRT is a great thing, but it has its down sides in my opinion..