I've seen those generation Kawasaki air cooled twins with hours in the mid teens and a couple over 2000 hours.

Change the engine oil and filter and air filter and do the other routine maintenance at the prescribed intervals and you should have no problems for a long time.

I have read recently blogs about carberator issues with the Kawasaki 20 hp engine in GT245's. The GX has this same engine but I really have not come across any such issues from anyone I know.

Is this really an issue?

With regular maintenance I had one go 1650 hours before the rod broke.

It was a real issue. I bought a used GT series (GT225) two years ago. Looked at a mint GT245 but it had the tell-tale signs (blew black smoke on start-up, blacked inner front rim, etc.). Mint tractor with 80 hrs, could have it for probably $2800, but I wasn't going to buy any known problems. I confirmed it with JD corporate that at least the one I was looking at was covered under the problem. I was given a range of engine numbers that were impacted. I read that jets could be changed, but created a lean-running problem for some. After that discovery, I limited my search to the GT225, GT235 and GX325. Unless you can confirm that the particular engine is covered, I think it would be susceptible.