Brian, My .40 is 53 1/2" long. That's with a 38" barrel. I find the length very handy in the woods. Unlike a straight barrel which can be very end heavy, I find the IH rifles with the swamped barrel to be so well balanced I never think about it when shooting.
My scales are not accurate enough to get a good weight but I'm sure it weighs between 7 and 8 pounds. It's not a light weight.
It sounds like a B-weight barrel in .40 would be OK. I weighed some of my rifles and shotguns, and I think anything under 8lbs is fine for my purposes. I have a CZ 452 in .22lr that comes in at 6.3lbs loaded, and that's a joy to carry all day. As you note, balance is important, and the weight of a longrifle is distributed over a much larger area than my little .22, which is a challenge to hold steady for offhand shots.
My .40 has a 38 straight green mountain barrel. The rifle weighs 7.5 lbs on my bathroom scale and balances at the entry thimble. It handles and shoots very well.
How wide is the barrel? Probably a 13/16" at that weight? I'm impressed at how light some of these straight barrel rifles are,
like this one Steve built.
For a first build I wouldn't recommend any of the kit rifles I listed. There is a higher level of difficulty than with kits like the Great Plains and other factory kits. The Kibler kit is the only one I recommend for a first timer.
Most likely I'll pick up one of Track's Isaac Haines kits, but Jim Kibler mentioned in his recent video they're going to produce a Northwest Trade Gun kit, and I may start there for my first build.
