too bad the powder companies didn't have a "sampler pack" small portions of powder enough for 20-25 loads rather than by the pound and being stuck with it if it doesn't work. --there's another million dollar idea there.
760 is faster according to the charts, i don't know if 760 will actually be far enough removed from 4350 to make that much of a difference in your short barrel. check out the .243 loads thread, perhaps there's a load there for a similar length barrel and in the same boat as you. i don't see a problem with using it, but would probably go with something faster just to make sure as your length is so extreme from published data.
i figure that your going to lose up to 50fps per 2", so if a load with a test barrel of 24" is listed for a powder, you can probably expect -200 to -300 fps from the highest load listed, so you may get around 2450-2650 FPS with 760 in your 16" using a max load and probably just burning up powder out side your barrel not really giving you anything back in return. a faster powder than 760 can't hurt, the trick is finding the correct charge.
looking at my hornady manual, it's lists 100 gr bullets through a 15" TC. perhaps look to two columns to the left to compensate for a 105 gr and 1.5" longer barrel for the powders they list. but again that's a guess....and is in the neighborhood of matching up with the estimated FPS on the rifle data -8" on the test barrel! so back to square 1.
things gets really funky when you start chopping barrels vs published data vs using a faster powder, as the characteristics change in a heartbeat.
whatever it is you choose to do, do it with safety in mind.
