I use the load from the straight conversion 1.33xC---IMR4831---93.1grs.-no filler. Depending on cases, there may be a little rattle-room left, and you might want to go to an even 95 grs., which is snug.
Anything less than the 93.1, might constitute having a little filler.
H4831 might give better density with the 93.1 grs., however I've never used this brand in mine, although I've heard it takes up a very "tiny" amount more space.
Also, this is considering a traditional 480-woodleigh. For other weights, it starts to become more confusing. And, also, it depends on your double and where it's shooting with this. This should be in the ballpark, if it's stamped for 480-70C. I say this, because at the moment, I'm using my loads in custom falling block actions I'm building up, and have not, nor will have to do any regulation testing, which is great from a headache standpoint. I have, however, had the opportunity to use this load in a double I had in my possession for a time, and it did well, as it was regulated for the standard 70C-480.
There is one thing I'm going to add here: RL-15, to me is better, if you don't mind using a filler, because it has noticeably less recoil. Maybe not enough to worry about in the .450, but from .500 on up, it's very noticeable. The one reason I use 4831 in the .450, is because I don't have to bother with fumbling around with fillers. Anything bigger, as in .500 to .600, and it's very much worth it, in my opinion.