If you really want to try a heavier sabotted bullet in the 45cal, look at Precision Rifle's 40cal Dead Centers or QTs. Cecil offers upto a 260gr but imo those are marginal in a 1-30 twist. The 240gr might work fine depending on the MV.

You could always choose a conical in the 360-405gr range. Those should work for you too. No Excuses sells a fairly affordable .451 385gr or if you cast you own, the old 330gr Gould mold will drop at about 350gr in pure lead. They used to offer that mold without a hollow point too which IMO is a better choice.

No Excuses
http://www.muzzleloading-bullets.com/index_files/Page319.htm

Precision Rifle
Dead Centers
https://www.prbullet.com/pts.htm
QTs
https://www.prbullet.com/qt.htm

Hawks offers some 40cal jacketed bullets over 200gr but his quality is rather spotty on his HPs and Spire Points. His flat points might be better but ive never gotten any.
http://www.hawkbullets.com/muzzlebullets.htm