You might get the Lapua 6BR brass for cheap enough over there to make it less cost prohibitive....but the 300 whisper does most of what a 302 does for much less investment. Load data is more readily available for the 300 too.
If you just have to have one....30BR reamer and dies will replicate it closely enough. You will need a throating reamer.
I've been messing with 338 in both the BR case and the 7.62X39
its nice lobbing the extra 60 grains of lead downrange and the accuracy is just fine
If cost doesnt constrain you 338 X 300 grains is good stuff.