Repowering my GTR 25efi Subaru with a 35 Briggs. A year and a half ago I replaced the entire efi system. Throttle body/ECU, both wiring harnesses and the entire fuel delivery system including the pump. It was $1200 in parts from gator tail. The engine has 247 hours on it. It runs perfect with absolutely zero issues.

Is it worth selling? Is it now a shed motor for eternity?

I sold mine for $400. I didn't invest the parts in mine as you did so little different feeling. I doubt you would be able to get much more for it since they no longer make the motor or support it.