Mark, everyone should own a 6 BR. Its sort of the rite of passage in the target world like the 222 is in the varmint world. Shoots lights out, barrels last a long time and in all but the absolute most horrid conditions, are competitive.
In long range BR competition, the Dasher or straight 6BR have won everything. The 6 Creedmoor and 6x47 haven't. And won't. Great at steel plate, but so are 223s and 308s as was seen at last weeks PRS match up here.
Lapua 6 BR brass, 205Ms, 30.5 grains Re 15, 107 SMKs seated for 20 thou jump in a 120 thou freebore chamber and your good to go. Works in every barrel i ever had and with the inclusion of 103 Copperheads, was exactly what i used to win at Narromine in 2013. The last time i shot a 6 BR.
The biggest decision will be to turn necks or not, but i guess no turn for the KISS principle. New blue box cases need a 0.270" neck reamer for a no turn chamber. Old cardboard boxed cases need a 0.272" neck. If you find old cardboard box cases, sell them to me, not that macca pirate
As a last note, bush back that Omark bolt head/firing pin to 60 thou. Most old girls are all worn badly to the point where loads a long way from approaching the high end, where you need to be, will blank primers. You will not get anywhere near the pressure or speed to make the 6 BR work even in a pristine Omark action. Trust me on this, you must bush back that firing pin. Under no circumstance use the recipe above in an 80 thou firing pin action. It will blank primers. This is what holds back a lot of 6 BRs and the like with small rifle primers.