Thanks for the input nuclearcricket.      

From the Greenhill tables I see a 15 twist stabilizes up to 366gr and up to 1.41 length in that caliber.     The 375166 is within both weight and length by significant margins.   If I’m reading & understanding the charts correctly I’m thinking the margin works in my favor but then again I read that “optimum” translates to the ‘slowest twist’ that will stabilize.      Does that mean then that a 15 twist is not quite optimum for this bullet?

I’m swimming towards the deep end here since my most extensive experience to date selecting a mold consists of sending a chamber cast and selecting LFP or WFP off a catalogue or style drawing.         

I’ve got a lighter and shorter bullet from a mold for my Marlin 1893 and it works fine out to 600yds.   

But I’d like whatever mold I settle on to be my cartridge for 650-1000yds.         

The Hoch 368310 or even the 377275 look like a good options too if they tailor dimensions.

Thanks again!