In recent years the .375 Whitworth has become very disireable. No problem building a .416 Taylor on one but personaly if it is an original Whitworth in the original stock you could probably sell it and find a realy nice FN from an early Browning or such like to build your conversion on. If you will look closely at the front of the action immediatly behind the barrel you will notice it has been notched out to clear the length of the .375 H&H. I have a .416 Taylor built on a Mark-X that is shooting 1" groups as is and I haven't finished load work-ups with it. Great cartridge. From my work with the .375 and .416 Taylor the Taylor has similar trajectories but hits noticeably harder and out penetrated the .375 but a pretty wide margin.

Whitworth with my LTD-V

my .416 Taylor under construction