I think you are looking at some serious differences between the original KT17 or retrofit onan and the 14hp kohler. IIRC the 314 was a single cylinder with a totally different sump/oil pan setup. The issues that you need to consider are:
Bolting it in
Driveshaft hookup to transmission
Pto placement for belt alignment to mule drive
Muffler placement
Wiring
I am not an expert but maybe somebody else can jump in with more info
Remember, nearly anything can be done to these tractors if you are willing to spend enough time and money.
Max