It should be possible. My tcp had a kubota oc95e diesel engine with a 25.4mm shaft. I replaced it with a honda gx630 (although a gx390 would have done ) with the same shaft.
Even if you have to replace the drive coupling and pump, their not a lot from flow fit. I changed my one because the drive coupling and pump spline was knackerd
Hi Russell, I have a tcp which I was thinking of swapping the oc 95 diesel for a gx390, other than the pump and coupling, did you have to change anything else like the hoses or control valves? I presume you have to live with out the 2 speed tracking too? There good little machines just got to many electrics on imo.