Several different medium burning rifle powders are so similar that for practical purposes, the same amount of either can be used. Many years ago I discovered that war surplus powder that Hodgdon's called H4831 had the same effects as Norma 205. When I discovered that with the same bullet, either 130 or 150, in my 270 and the same weight of powder, either H4831 or Norma 205, no difference in drop could be detected at 500 yards, I just considered them as equal. I sometimes thought the 205 had an inch less drop, and yes I did make the odd MOA group at 500, and this was long before the computer could be used to tighten groups! Ever since, I have interchanged loads between the surplus H4831 and N205, but 205 usually gets the nod, because of its much greater density. The modern H4831 is slower burning than the old surplus.
I found the same correlation between IMR4350 and Norma 204, so I will interchange those two anytime, but in this case 204 does give a bit better velocity.
When I was building loads for a 7-08, two powders I was using was Norma 203 and IMR 4064. I soon discovered that the same amount of either powder gave the same readings on the chrono, well within the allowance for tolerance of the machine. and this was with several different weights of bullets.
I have an old Norma loading chart where they use both Norma and US powders. With the same bullet in the same case, they rate the exact same pressure and exact same velocity, but 2/10 of a grain difference between weights of either N203 or IMR4064.
And that is well within the caveat I used of, "for practical purposes." Several other powders in this area will be between 1 or 2 grains of being the same.