Padre,
My book shows the Model I early 110/140 shows 2:1
Model 140R s/n above 2791957 shows 1.98:1
Make sure the transom assembly is compatible. I found the Alpha drive was not compatible type I-C EZ transom assembly.
I don't know if simply changing out the transom assembly would allow you to go with the early Alpha which may be far easier to find parts for.'.
These ratios come from the Seloc manual because I couldn't find the info in the Mercury Manuals.
Err, are there moral implications relative to the insurance history

?
Let us know what you find...