Small Engines (Lawn Mowers, etc.): replacement engine for craftsman lawn tractor, craftsman lawn tractor, tractor models

Question
I have a Craftsman lawn tractor model 917.270670 with a blown motor. I found a model 917.270940 for sale and was wondering if the motors would be interchangeable. I think it has a 19HP motor, vs the 16HP that was in mine. I know some of the B&S motors are interchangeable, but I cannot find any info at all on the model 917.270940. Google comes up with next to nothing on this model. Do you know if the motor in that model will match up with my tractor?

Answer
I can't find any specs on the crank size for these motors.  Everything except the crank have the same part numbers.  Even the block is the same.  If the crank measures the same this should be an easy swap.  The 917 numbers are tractor models not engine numbers.

The 270940 has a Briggs engine model# 461707-0145.  The 270670 tractor has a 310707-0136 engine.