Galion 118B – need replacement for Cummins 743

Hi! I recently purchased a Galion 118B grader. I paid $3500 for it. It's basically in working order, however the engine is on its last legs, has a bad cylinder and blows oil, smokes like a steamboat. It seems like parts for these engines are not available so I am looking for a replacement. So what kind of engine will fit? What do I need to look for to make sure it fits my grader? The most obvious choice would be a mild big cam - either a NHC250 or NTC350. Scanning the posts here on the forum I see some folks who put 4-cyl turbo cummins and even Detroits in place. Does that mean pretty much any (class 8) truck engine will fit the transmission and clutch? As a side question, is the $3500 an ok price? Kids smashed the windows and instrument cluster so it's ugly but functional. Most functional graders seem to go >10k. I found some real old early 60's Cat graders in the $6k range but they didn't have the hydraulic controls. The Galions seemed to have the better setup at the time, although now the Cats seem to be worth more - I presume because of parts availability? This is one thing that worries me about this machine..