Brokennock
Cannon
You raise a good point.It may help your powder to think about what is printed on modern shotshells that you might use - the "drams equivalent" markings.
One dram is 27 grains of powder.... so a 54 gr load would be the 2 drams, and the mid 60s would get you the 2.5 dram that quite a lot of modern "light" field/target loads claim to duplicate.
But one also must keep in mind that modern thinking is that more and bigger and faster is automatically better, so we see a lot of 3 and 3 1/4 equivalent shells, even in smaller gauges. So? These dram equivalents give the marketers bigger numbers on the box for both powder charge and velocity,,,,, but that doesn't mean they will pattern well, and, those shells have shotcups designed to try to improve those patterns.
It might be interesting to look for older boxes, even pictures of older boxes, of shells that predate plastic shot cups and see what dram equivalents they were loading then.