My preference is the Hunter bench rest .
It has a faster taper (.024 per inch insted of .015).
but will only finish to 27'' . This makes for a very
ridged barrel that is not to muzzle heavy.
27'' of barrel is about all you need for the big 300 for all
around performance and manageability with the heavy
As Wildcat said Lilja can make you a longer barrel and contour
it how ever you like but I think your on the right track.
Plus if later on you decide to put a muzzel break on , it will
still be under 30'' long,
J E CUSTOM