I think you will like the Lee bullet. But, since your velocity will be higher, I would suggest gas checks and/or powder coat.
If you can find someone capable, the Lee molds can be machined to make them a plain base. But, I would still suggest powder coating for higher velocities.
Something else to think about. "In the old days" we used polyethylene wads behind magnum bullets without gas checks. They were about 2mm thick and cut to a bit larger than bore, a tight fit in the case. The wad was placed in the mouth of the case and the bullet pushed it the rest of the way. The wads protected the base from powder gases.