@xploder98
Just asking 'cause I'm curious, how many miles on the OHV Engine?
With regards to Commercially Available on the shelf rebuilt OHV's , I haven't read about any particular brand that offers the mileage that you get from the factory original, German built engine.
10 to 12 years ago, you could stull get a factory FORD long block (from FORD) that utilized all the original German parts, but those days are long over...
Bottom line w/ regards to the commercially rebuilt ones; most will have a majority of Chi-Com parts, that don't hold the close tolerances of the original German parts.
From the experiences that I've read here with guys trying to keep their "daily driver" running, you'll spend about $2,500 (+) Labor to get about another couple of years out of your Ex.
What stands out to me from others experiences is that quite a bit of the re-man engines have noisy valvetrains right from the first turn of the ignition key - due to the loose tolerance hyd. roller lifters, soft push rods, and soft rocker arm "cups" (where the rocker arm connects with the push rod).
Also, I recall reading a LOT of cases of "piston slap" - again due to loose tolerances - this time with cast pistons and cheap rings.
I can't remember how many times I've read about a guy putting all the $ and time into installing the rebuilt engine, only to quickly post right after installation something like "why is my re-manufactured engine so noisy" or "why is my remanufactured engine running so rough"?
They are forced to "settle" because the rebuilt engine company says "they're all like that" ....
Then, after a couple of years, the "pita" problems start to emerge; cheap gasket problems such as timing cover gasket (BIG pita - factory original is Teflon coated green paper and rebuilders just use regular paper), bad water pump, oil pan gasket leak, oil filter adapter leaks, etc...
When I came to the point where you're at - factory heads going bad - utilizing mine as a "daily driver", I realized that I was at the point of diminishing returns.
In your case, if your Ex is just an off-road play toy (as opposed to a daily driver) then perhaps you're willing to forgive any inadequacies in return for the off-road utility you'll get for a few more years.
Not saying that you can't get a off-the-shelf rebuilt engine that will meet your standards, just saying I've read a lot of guys that daily drive not being happy with their replacement powerplant (compared to the factory engine).
Hope that helps w/ your decision