IO540
Yes it would, the crank looks serviceable to all intents and purposes, however when the crank itself is spun on a test bed, it bends at certain rpm's notably within the normal operating ranges. its a strange effect, but one which I have actually seen proven by a guy who does prop balancing and RTB work freelance. He did the tests on several shafts in conjunction with a crank balancing specialist from Bicester, it was scary to watch.
Your other point about "agricultural" tolerances is correct, these engines do generate vibration from idler gears, pistons etc, however the frequencies and amplitudes are usually undetectable by the pilot. As I said, the guy I knew does a full vibration survey of the engine, and he can pinpoint any real defects. One thing I do know is that the tolerances you refer to, do not prohibit prop balancing. As I said, having seen this one particular guy in action, I recommend him to anyone.