80 is THE powder Mr Keith was using when he developped his .44 Spl loads.It is faster burning than 4759(which can also be used in .44 Mag but is too slow to get good performance from).The fact that 2400 supplanted #80 when it came out is well documented history but #80 must be the powder that ''started it all''.
Since 2400 is slower burning than 80(as per Mr.Keith sayings),I think that you can look up any starting load of 2400 and start '' experimenting'' from there.
Old data was for baloon case heads though.You'll have to make up for that if you rely on old data(1920's to 1940's)