Since it's a ML .. not a MLS, will you be upgrading it to a 209 conversion? If so, buy the Cabelas conversion... no other one if you're looking for best performance with pellets.

As far as bullets go, your "likely" bore size indicates you should stick with T/C, Traditions or Remington-packaged bullets for a better fit. Sabot/bullets between 200-300 grains should work fine. Avoid Remington-packaged bullets if you plan on using magnum powder charges. Their plastic sabots usually don't support the generated power very well. They seem to be going out of the ML-accessories business I've heard... rumor has it that it may include their ML rifles very soon too -- due to a lack of sales.

As far as powders go, look at my screen name. It's the best... buy the loose jug in FFF... works in all my calibers from 45-58.

Good luck & make lots of smoke!