Small Engines (Lawn Mowers, etc.): JD 345 engine, john deere 345, specific designs

Question
I am having some carburetor and coolant leaking problems with my FD590V Kaw. engine on my John Deere 345 tractor.  I also learned it has a plastic cam that tends to break at the hours I currently have.  Should I replace the cam or just get another engine?  If the latter, which engine is good?  I hear the 590V is discontinued and the Kaw. replacement is not identical and has to be retro fit.  Can you advise?

Answer
Tom:

I take it your approaching the 1100 hour mark on your engine is that correct?   Its a piece of cake to replace the cam.  If memory serves me right it is a steel cam in place of the plastic one that broke.  

It will be very difficult to put a different engine in that tractor due to some very specific designs by John Deere.   Time for a good tune up.  A new engine will be quite costly.

Great Tractor!