I have hunted in the thick stuff for decades. Have killed multiple deer with 223, 243, 7mm-08, 308, 30-06, 35 Rem, 444 Marlin, I won't go on. There's many more.
Point being, they all work with the right bullets/shot placement. Pick one. But pick one in a light, fast handling, accurate little package with a 3-9x40 scope at the very, very, largest. I like the 1.5-5x20s and 2-7x33s both with heavy duplexes, when hunting the thick stuff. But use others as well.
The tang safety Ruger 77 (as mentioned) has taken a bunch of deer and continues to do so. With 100gr SGKs it has produced some very fast kills. As for 30-30s, I have 4 of them, and don't use any of them. Not that they won't work. A bolt action 30-30 would be LAME though, IMO.
Given that you have a 30-30 and a 243, something like a 338 Federal would be pretty cool in a bolt gun. I do not own one, because I have too many rifles as it is, but think it would really shine in the thick stuff. It can also be loaded to shoot much flatter than many may think. Or just get a 7mm-08 or 308. Can't go wrong with either.
As for your 30-30, if it is not a pre-64, use it and don't sweat it. I regularly hunt with 2-3 pre-64 Winchesters (not 94s or 30-30s) and love them both. That is what they were made for.....