Are you sure about the internal differences with the turbo engine? I'm in the process of putting a turbo on the D1105 in I'm my B2620. From my research the only real difference between the turbo and non turbo on my engine is the timing of the injector pump and the injector nozzles, besides the different injector lines to clear the turbos version intake.
Like you I'm looking for a little more pto hp and better efficiency.
I expect about a 5-8hp increase at the pto.
Internally the D1105T has different pistons with steel ring lands and black coating.
This place can have good deals on Kubota engines from time to time:
Kubota Diesel Engines | In Stock New or Remanufactured Diesel Engines