I currently have 46,311 miles on my 1993 TW with no overhaul, a valve job was the most major work. I do recommend checking your cam chain guides at around 40,000-43,000 miles. I did change my cam chain guides at 42,000 miles when I did the valve job. I recall someone else had 50,000 and then swapped their engine out. I think they had damage from the worn cam chain guides where it caused a timing jump or similar damage. Keep that cam chain tensioner adjusted to spec.