I've always found that weight, not length, is what makes the gun "handy". If brush is so thick that length makes a difference, one might want to get out of the brush! My 1861 is one long drink of water, (40-41" barrel) which has never annoyed me. I can thread my way through thick stuff with it just fine. But the 10 pound weight does discourage me from taking it out sometimes. Ten pounds is getting up there. Nine isn't so bad. (one pound can "seem" like a lot of difference) I like long guns right in the 8.25 pound range, which both my Jeager, and Brown Bess carbine are. 34" is not a long barrel. On the other hand, a 30" barrel is not a stubby barrel.
I understand that if one really likes the rifle, some modifications and cost might make more sense rather than just getting another rifle, and letting that one gather dust. It sounds like a very nice rifle. I would not hesitate to make it more to your liking, as long as you think it out well, which obviously you are doing.
If you are going to cut it down at all, I'd take at least 4" (or 3&15/16ths) even if it just "seems" lighter, the psychological effect might make it more pleasant to pack around. Reducing muzzle weight will certainly make it "seem" lighter.
I really like the idea of both taking off 4", and boring the rifle to .58". That...will make a difference. The cost would be more than worth it to make a rifle that you really like, into something you really love, and love to use. Having the barrel cut, bored, and rifled all in one shot might even save a buck or two. Do it.