Get set for some humdinger recoil. Be mindful that unlesss Hornady has toughened up those bullet jackets just abit you won't get back much more than 130 grs of shrapnel from those 300 gr bullets.
If that rifle is drilled and tapped for receiver sights a Williams for the 86 win should fit right up. I put one of the Ukranian lyman 38 type sights on mine. had to wait a year to get it. If you want a version of the Lyman 21 might look at Providence tools version.
Cast bullets are easier to come by now than 7 or 8 years ago. Buffalo Arms has a pretty good bullet and mould and Lyman has returned to making the 412263 bullet mold. Montana Bullet Works also sells good cast bullets for it, but you may want to slug the barrel for a measurement they have been running pretty large the last couple of years.
Best powders I've come by for cast is 5744 and rl12 for jacketed. Rl12 isn't available anymore, so subbint rl15, or 4320 works pretty good.
Fun cartridge accurate as the dickens, and kills elk plumb dead.