I'll have to second Jim's post, I had quite a bit of success running more than 10:1 on a street 400, with a RAIV cam to keep things under control and really work the mid and upper rpm range.

Same thing, zero deck, attention to detail and proper tuning resulted in an engine that I had to purposely put heat into before running it hard. And yes, we do get above freezing up here!

That being said, doing the same things with a 9.5:1 engine gives more wiggle room if the tuning isn't as good as it should be. A little less compression is a lot better than a little too much.

Q, the jury is still out about the switched firing order, some engines like it, some don't. I haven't done any back-to-back testing yet.