gathumper,
You are very welcome here and don't think for a minute that you would be making a pest of yourself by asking or answering questions about double rifles or anything else for that matter.
That's what the site is all about and the more you post the better!

There are quite a few members here who have built or are building their own doubles and I'd think they would be happy to help out with any info you require.
A scoped 9.3x74 and an open sighted 450-400 NE 3" would make a very nice pair.

Welcome aboard!