They are very durable engines, now finding parts is a chore though, It took me a couple hours to find a new replacement carb for one at work thats mounted to a Mikasa tamper. The carb shaft was frozen completely and I couldn't free it up. I had to cross refrence some old part numbers I found and was able to get a new carb through Oregon.
The durabilty, I can attest to, this engine is a 1992, its got hundreds of hours on it, these a-holes at work never bring it in to change the oil or anything so they take the abuse alot of other engines cannot. Reason parts are hard to find is because they got bought out a couple times and Subaru now owns them, and Subaru only makes OHV engines now, no flathead stuff and they dont have any parts for them really. From what I gather they stopped making these engines in the early to mid 90's.