If you want to answer your own question just go to any site on the web that deals with long range rifles, precision rifles or custom builds and see if you can find even one that was done using an the British Enfield action.
If you ever find one, let me know as I've never seen one yet.;);)
Gotta agree with Roy, keep 'er as an original and enjoy it. Not too many shooting the 303 now so you'd have a unique shooter.