Thanks for the informative replies.
So, you guys suggesting that I go with a 24" barrel with a slow twist? Think it will look OK with a standard length mag tube and a round barrel? Or do I need to look at installing a full length tube as well? He starts with a 22 caliber barrel blank and I'm pretty sure he can make it any length I want. Nonneman Custom Rifles is who I've been talking to. According to my local gunsmith, $475 for the conversion is pretty decent. My smith would have to buy the reamers and that would put the project out of the price I've been quoted.
I've got larger bullet lever guns already...30/30, 44 mag, 454 Casull, 45/70, so I am thinking this will be a light bullet gun to fill in between the ones listed and my 22LR. Someday I will get a 22 Mag as well in Marlin. So I'm thinking 8o-100 grains max with priority given to the 80 grain side for accuracy. I could have a 219 zipper made for the same cost, but I am thinking that in my part of the country that the 25/35 will kill more than paper.
This being converted from a 30/30 Texan with straight stock. I'm a straight stock guy. Just cannot warm up to lever guns with a pistol grip.