Looks awesome Dave. I'd be tempted to say you're lucky, but it was persistence and not luck that got you this setup.
By the way, you can get a grey to hold together (at least for a little while) at high revs using the Vauxhall L model crank. It is a bit of mucking around BUT my engine builder knows how to do it, if you're interested. A good crank is cheap but the machining involved is not. However, it is much cheaper than getting a custom crank machined out of billet steel.