Jim, I think if it wasn't for bad luck, you'd have no luck at all.........any rebuild should last longer than 4000 miles........
Maybe you stated it earlier, but what
oil pump do you have,standard volume or high volume???
If the valves are caked with
oil and I've seen this before it is either your guides or seals or a combo of both,the heads will need to be checked out thouroughly......
And I'd still run a hone down each cylinder if nothing else the type you attach to a drill,just to make sure there is no glazing on the cylinder walls.....
Cam/lifters showing enough wear to be replaced after 4000 miles,(what type cam/lifters) something isn't right here, I think I'd find another machine shop/engine builder...
David