I tripped over some square tubing on my garage floor, and I decided to make a crankshaft holding fixture.
After about 8 hours of futzing around and $15 in some nuts and bolts, the (semi) final product...
M12 bolt threads into the crank snout and "floats" in the fixture.
5/8" bolt threads into the fixture and the unthreaded portion (can't be seen here) locates in crank.
It's not pretty, but functional. Since I can't find my flywheel right now, this will come in handy for when I start checking clearances and bolting up the rods.