More important than anything else; with the Marlin M336 you’ll want to size your bullets NO SMALLER than .310”.
I shoot .311” bullets in my Glenfield (Marlin) M30. It will go as high as 1400fps with the Lee 120gr RNGC WITHOUT a gas check. (Not pc, rather Lee liquid alox). About 8.0gr of Unique. With a GC,and SPG lube, I’ve gone as high as 32.0 gr of RL15 for 2,300 fps.
Secondly, max oal to function in a Marlin is 2.585”.
I also recommend a Lyman M-die and a Lee FCD (factory crimp die).
With 30.0 gr of RL15 or 27.0gr of 3031, the Lee .311” 150gr FNGC at 2,100fps shoots under 2” @100yds. A Lee mold will run you $30 now. A .311” sizer die $24. Less than 200 jacketed bullets.
I could have killed 95% of the big game I’ve taken over the past 47yrs since I bought my my first Lee mold... even unsized with LLA, over 7.5gr of Unique they’ll shoot minute of coke can and have killed deer... think .357mag revolver power!
A 150-170gr cast bullet is all you really need in a .30/30. A medium hard cast bullet performs about like a premium hunting bullet.