(I posted this in the medium bore forum, but I thought it may be worth posting here as well).

I noticed on quick-load that the case capacity of the 9.3 X 74R is ~84 grains of water, compared to ~88 grains of H20 for the 9.3 X 64.
This got me thinking: why not "hot-rod" the 9.3 X 74 to more modern pressures and get w/in ~100 fps of the 9.3 X 64? A 250 gr Nosler Accubond (or Barnes TSX) at ~2600 fps would make the 9.3 X 74 a legitimate 300 yard cartridge.

With modern quality brass (i.e. RWS or Norma), is there any reason potential problem with doing this in a Ruger No. 1? I can't think of one, but I thought I would doublecheck before I do something stupid...

Work your way up slowly and see what you get.
You won't be doing this in a double because of the obvious regulation concerns.
One thing to keep in mind is that the shape of the 9.3x74 case is long and tappered. Even if the cases and and gun can take the high pressure you will get more back thrust from the 9.3x74 case than you will from the 9.3x64 case so you won't be able to safely equal the same ballistics of the 64mm case.

The No.1 action can certainly take the pressures you're proposing. The x64 case is fatter and will stress the action more like a .338 Win Mag, which is a standard chambering. Your more slender x74R case ought to stress it less at the same pressure (I don't subscribe to the Ackley breech thrust theory).

Elmer Keith's .338 wildcat on that case ran at the higher modern pressures.

Case life might be poor if you're not careful in resizing. The shoulder isn't much, but you might be able to headspace on it.

You might measure the capacity of a case fired in your chamber. In the 9.3x74R, several gn of water variation has been reported among different makes of brass.