616,620,720,4040,9020 Onan Engine Summary

[Les]

As previously discussed, I am trying to put a summary together about how to deal with the Onan CCKA and CCKB engines. The engines sold to AC/Simplicity were speced differently and Onan has not been particularly helpful at providing parts which creates a major problem in trying to keep these tractors running. Stan, Roy, Mark and others have provided some facts which I have tried to summarize here. Please comment on the accuracy of this information;

1. Crankshaft size is 1.437" and does not interchange with any other engine. Any engine swap would require special machining.
2.The front PTO clutch is a major concern, as it bolts directly to the front of the engine block with close tolerances. Since it is electric, volts and amps(front a possible different engine) are of major concern.
3.Base mounting bolts are spaced at a rectangle of 7"x12.25". Crankshaft height is 16.875". Overall engine height is 22.25", width 20.25", engine platform to shroud is 22.25", muffler & exhaust extend forward 10.25" past PTO pulley.
4.The major problems associated with an engine swap are alignment of the front and rear pullys and the mounting/operation of the electric PTO clutch.
5.One of our dealer/members(Mark-- twaite@gateway.net or 248-373-7220) states that a short block is available from Onan.

The major question as I see is: Is it possible for an Onan CCKA or CCKB to be rebuilt using the Onan shortblock?

If not, what kind of engine can be used in it's place?