I am looking at the Sierra manual as I type and I see no info for WW760 listed for the .303 with a 174 SMK.
They list their accuracy load as 40.7 gr. of 4064 which is the book max with that powder.
My old Sierra manual (1977) doesn't have data for 760, but the Speer #10 does. All the following loads were developed using the CCI 250 Magnum primer. The velocities shown are muzzle velocities measured in a 25 1/4 in. barrel.
Speer 150 g. spizter:
grains 760 mv
start 44 2319
max 48 2575
Speer 180 g. roundnose:
start 41 2197
max 45 2439
I'm having trouble making my neat little chart look right. Hope this makes sense.