Oh nice - hope the .003" taper per side is OK.

My .375/06IMP has only .005" taper per side and it's better than fine - love the straight cases.

Of course, you're aware that the minimal taper means virtually no bolt thrust and other pressure signs are needed to be heeded - with this litle taper, pressure signs can be virtualy invisible. A chronograph is absolutely necessary when developing loads.

I'd think, that at 88.8gr. capacity, you'll easily match H&H factory and perhaps exceed it a bit - safely. Is it necessary, though?

Varget might just be one of the best powders for it, but the case capacity is pushing into slower yet powders. It should easily deliver reasonable speeds.

It would be nice if you didn't have to use the 4350's and compressed loads.

DIES - a Hornady seater die will work for any .375.

As your shoulder is larger than a .376 Styer, their sizer will only be VERY useful in initial necking of brass. You could perhaps lapp out the shoulder area, changing their sizer into the proper size for your round.

If Hornady makes a neck sizer for the .376 Styer, it will more than likely work perfectly for neck sizing your round - or you could have tham make you a sizer - probably around $100.00. Some guys don't like them (apparently), but I love my Hornady dies. They are straighter than any green box (RCBS) dies I ever bought.