full case load,
Checking for Blue Dot loads in the 327 Federal Magnum, I found none. That includes my copies of Handloader Magazine, where Brian Pearce worked-up loads for the .327 using several faster and slower powders, but not Blue Dot. That may or may not mean anything.
As for Blue Dot data for the .32 H&R Magnum, my Hornady 4th Edition Manual, printed in 1991, does show Blue Dot with a 85 grain jacketed bullet (#32050 HP/XTP). That manual uses the velocity table format for charge weights, rather than the more common "start" and "max" format. The data range from 4.4 grains giving 700 fps (which is the lowest velocity used in that table, but not necessarily the minimum safe charge for that powder) to 6.0 grains giving 950 fps (which is a maximum charge, rather than the highest value the table goes to). The velocities were obtained using an H&R revolver with a 4" barrel.
Doing a little math: The Hornady manual specified a COL of 1.360 for that load. QuickLOAD indicates a default powder space with the capacity of 13.172 grains of water when that bullet is seated to that COL. And, QuickLOAD indicates a default powder space with the capacity of 15.970 grains of water when the same bullet is seated to the same depth in the .327 Federal Magnum case. So, with that particular bullet, the Federal case has 21.2% more powder space than the H&R case. In comparison, the range of charge weights in the Hornady manual is 36%. So, at least with this data for this bullet, when the "two-thirds-of-the-way" charge of Blue Dot for the H&R case is put into the Fed Mag case instead, it should give about the same pressure as the lowest charge weight given for the H&R case when loaded in the H&R case.
So, normally, I would say that it would be a "go" to start there with this particular bullet in the .327, given this data. HOWEVER, this data preceded the withdrawal of some of the Blue Dot data for some other, similar cartridges. So, I would urge more caution in this particular situation. And, if the H&R Blue Dot data you have is for a different bullet, then these calculations are not necessarily applicable to your data.
Normally, the thing that I try to do when faced with your type of question is to adjust the charge weight in the data to keep the "load density" the same for a change in case capacity. I use that for capacity changes caused by changing seating depth as well as for going between a standard pressure cartridge case and its "magnumized" version that is stretched only a bit just to keep it from being chambered in a gun not designed for "magnum" pressure. For small changes in case capacity, that tends to keep the pressure roughly the same. Actually, it tends to be a little higher when you are increasing case capacity and a little lower when you are reducing case capacity. So, don't go to very large differences in case capacity when using that method.
For those reading this who don't know the definition of "load density," it is the ratio of the powder charge weight to the powder space volume, where the units are typically grains of powder for the charge and grains of water for the powder space volume. But, any units will do as long as you use them consistently and get the same number for both cartridges.
SL1