I have done so for those two rounds myself as well as with several old Winchester rounds including the 6mm Lee/Navy and a number of European rounds back in the pre-Internet Dark Ages. Phil Sharpe's books were helpful as we're old Lyman manuals. Cartridges of the World and an old book on cartridge conversions also helped a lot with some basic loads. When I first got into the 303 Savage and Remington's 25, 30, and 32 rounds I did much the same as I didn't know at the time how similar they were to common Winchester rounds.
As an aside, have you seen Mike Venturino's article on the 351 WSL in Handloader Magazine a couple years back? In it he discusses using Accurate 5744 in that cartridge and gives a general mention on using it in other places.
Also, what are you using for your 401 brass? I want to make more of my own one of these days. I have brass on hand made by others out of both 35 Rem and 7.62x39. I don't have forming dies but do have reloading dies. I'm tempted to fire form some 7.62x32 brass but not sure that will work.
I'm not much for technical knowledge or ability but I do my best to research and think before undertaking a project. So far I have not harmed myself nor a firearm but I'd be surprised if I haven't occasionally fallen into the ignorance is blis category.
I have used some 7.62x39, but have not finished them, I think they need fire forming to be good, have ordered some from the states made from 7.62x39 by an outfit down there, will compare to my effort, but I also picked up 414 super mag brass and that seems to be the easiest way to make them, I trim to length, and trim down rim on a drill press or hand held drill.
I also ordered some 6.5 grendell basic brass to try, it is a straight wall that can be made into various bottle neck cartridges, but I am going to use as straight wall.
for my 351 I bought Jamison brass when available years ago, but have now been playing with 360 dan wesson brass, that you just have to trim to length and reduce the rim, they look not bad, but only shooting will tell how successful I am going to be.