Exactly what are you wanting to do with a heavy bullet load in the .30/30?
The heaviest bullet I've loaded is a Lee .309 170gr FNGC, which from my mould with w/w metal runs 178gr.
I've loaded it over 28.0gr of RL15 for ~2,100fps. This load is the fastest I can run it and still get good accuracy (2moa at 100yds).
This would work on most anything you'd need to shoot including Moose at close range or personal defense on bear.
This bullet seated to the crimp groove is the longest bullet that will feed through a Marlin or Winchester l/a. I've shot deer with it and it completely penetrates, every time. Without hitting bone, expect to trail them, however...It dosen't expand much, just punches through.
This bullet over 7.5gr of Unique, GreenDot, Herco, or Hod. Universal without a gascheck is a plinkers delight. Cheap, not so loud, and accurate.
However, I prefer the Lee .309150gr FNGC as it's slightly shorter, just as accurate and works just as well on deer.
I size them to .311" and use Lee TumbleLube on the "plinkers" and SPG on the gas-checked full speed loads.
About 20yrs ago, Sam Fadala wrote an article for Gun World. He talked about using some 190gr RN jacketed bullets originally intended for the .303 Savage. He had to re-size them from .311" to .308" before seating them. For some reason I want to think they were Winchester component bullets. Not available now.
fwiw; A poster on the marlinowners.com forum did a test on the commonly available bullets for the .30/30.
He found that the 170gr Winchester SilverTip gave the best penetration, followed closely by the 150gr Barnes TSX. The Remington 170gr Corlokts and Nosler Partitons were close behind.
I've used the 170gr Corlokts with excellent performance. They are about as good as you can get in factory ammo for the .30/30. I would use these before I would the Noslers. You can buy 200 Corlokts for what 50 Noslers cost.
I doubt that any 180gr RN or FN will do anything better than a 170gr Corlokt or Sierra 170gr ProHunter, and wouldn't likely function through a l/a unless crimped in with a Lee Factory crimp die. The cannulures on the 180's will be in the wrong place for the .30/30 and velocity will be too low.
I'd suggest investing in some 170's and LVR powder. If not LVR, either H4895 or Reloader 15.
For a cast bullet, RL7,RL15, or H4895.