I have a 1976 vintage Model 336c in .30-30. This rifle would be similar to the original poster's 336w except for stock material, being a having a 20" barrel, full-length magazine tube, and two "barrel bands" in its original form.
Mine was a sub-2 M.0.A. grouper with just about everything in its stock form. Still, here's what I did to mine in the hopes of maximizing its "long range" potential with Hornady LeverEvolution rounds....
I had the magazine tube shortend to half length or "button" style. The magazine is tube is now retained in the same fashion as that of an XLR or MX model. This eliminates the need for the forward carbine style barrel band and takes a pressure point off the end of the barrel. My original mag tube follower spring was shortened and re-used. I had a new orange plastic LeverEvolution friendly follower installed. The rearmost carbine barrel band was retained, but it was slightly relieved in its interior diminsion where it goes around the barrel to provide a little room for the barrel to expand and contract as it heats and cools. I also had a QD sling swivel stud mounted to the bottom of the remaining carbine band. I had a LimbSaver recoil pad installed, which does nothing for accuracy for me but does let my kids enjoy shooting the rifle without getting battered by recoil. The buttstock was then glass bedded to the tang. Finally, a Williams 5D peep sight was installed and the factory buckhorn sight was removed with dovetail blank fitted in its place. The trigger on ths rifle was always nice, breaking crisp, clean, and creep free like the single action pull on a Smith and Wesson wheelgun, at about 3 /12 pounds of pull, so it was left alone.
The rifle is now 3 in the mag +1 in the chamber for 4 shots. It will group 4 Federal factory 170 grain rounds right at 1 minute of angle. 160 grain LeverEvolution groups inside of 1.5 M.O.A., which I think is entirely satisfactory for the use that this rifle is put to. I'd like to scope it one day and see if it groups even tighter, as I think I'm at the limit of what my unaided eyesight can resolve at distance without optical magnification.
I am happy with the rifle and with the LeverEvolution ammo, it has the accuracy and terminal balistic authority to cover all of the hunting that I m likely to do now and in the forseable furtue. It isa joy to carry and even more fun to shoot!
T-C