A link to the articles by John Albert aka ‘35 Remington’ has been provided. There’s lots of good info there. Other useful 35 Rem articles are those by Glen Fryxell and Paco Kelly.
The current factory pressure is held to low levels because of problems with some older firearms that predate the Marlin 336. As mentioned, in a Marlin 336 that’s in good condition, there is no reason not to boost pressures to those of 30/30 factory rounds. Buffalo Bore ammo features a 220gr Speer at 2200fps.
I have had good results with cast. With Marlins that have micro groove barrels the usual cure is to use a bullet that is larger than the groove diameter, use a GC design and a hard alloy. I’ve used a Saeco 352 design to great effect. It’s pretty heavy and seems to be tailor made for the 35 Rem / Marlin application. My bullets weighed 247gr and were sized to 0.360”. Using 35gr of AR2206 powder I reached 2000fps with this bullet and accuracy was brilliant. This powder is some 3% faster than its replacement AR2206H (=H4895). I have also used H4895 but accuracy was not as good and velocity was down. I’ve not tried it but IMR 8208 might work well with this heavy cast bullet.
When choosing cast bullets just be mindful that the Marlin chamber has no throat, so designs with a long front drive band are likely to foul. Even the Saeco design that I used had to be crimped into position using a Lee FCD to make it function.
