John deer z520a engine

[Lumar19]

Hi, I am new to this forum and I have a question for anyone who knows the answer.
I have a zero turn John deer z520a with a Kohler sv730 engine. The engine has a hole on one side of the block and I need to replace it but I can’t find the same engine because it is discontinued. My question is what other engine fits my mower?

 

[Scrubcadet10]

Main thing is , if it has an electric PTO, the charging system needs to be at the minimum same amperage as original, Most bolt patterns are standard for certain HP ranges, next thing to consider is Crankshaft Length and diameter.
and dimensions of the Engine in case they have it jam packed in the mower.
All of these specifications you can probably email Kohler to get them... And see if they have an engine that will work, or if you want to go with a Briggs And Stratton or Kawasaki.