That ought to make a great cast bullet rifle. A buddy of mine and I got together to shoot some cast bullets in his rifle. He brought the primed cases and I brought the bullets, powder and dies. I just arbitrarily picked 10 grains of IMR 4227 behind an Oregon Trail 170 grain bevel based cast bullet. We shot at the 200 meter chickens and it was deadly accurate with the recoil of a 223.
I just looked in the Neco Quickload Software for ideas with IMR 4198. With a 214 grain cast bullet (Lyman) and 25 grains of IMR 4198 you should get about 1800 fps. The pressure of this load will only be in the 20K area with 55K being the maximum allowed.
I would work lower and some higher than the 25 grain loading. I use 4198 for reduced loads quite often (as recently as today) in some of my loadings.
Another great powder would be Reloader 7. 25 to 30 grains of Rel 7 will give you about 1733 fps to start with pressure in the 17K area. I don't know what you want to used the rifle for, but if it is for target shooting, keeping the velocities down and recoil will be nice to you.
Harold Clark