I just did that for my Briggs motor. If your engine was running like new before the incident, then it should be worth investing the time and money. Some tips I have are, Don't be in a hurry, it took me a few times to get it together right, I believe my biggest mistake in this is that I reinstalled the mower blade that was on the mower at the time of the damage, causing the blade to be bent also. The racket it created at startup caused me the several tries to reassemble correctly. Also, the engine will not allow itself to be pulled without the blade. It seems to act as a flywheel for the motor, so you should replace that with the new crankshaft. Make sure the dots line up on the camshaft during reassembly and all should be fine.
TJBEATY
September 2008