I'm curious about how you have 0.4 ips vibration problem?

I had it tested at an FBO that does prop balance and they found about
0.2 ips at the prop (FAA acceptable) and about 0.4 (+?) ips at the
other end and told me it was the engine.

Are you sure its the crankshaft?

I didn't actulally say it was (only) the crankshaft. But as Ben said I
could probably do the pistons/rods myself with a good scale. But
balancing complex rotating masses like a crankshaft requires a proper
machine.

Sorry, I disagree that automotive people can do a better job.
How many auto shops check the nitriding and heat treatment?

The issue is balance not other engine work. Auto shops balance engines
to 6000+ rpm redline, whereas aircraft engines redline only to about
2800. Search through this group and you will find some interesting
discussions about lax approach to balance by Lyc. etc.

Pistons and rings are not part of crankshaft balance. Pins bearings?

???

The whole engine balance is made up of pistons, rods, bearings, rings,
crankshaft, moving masses which need to balance together.