I'm interested in trying to build a load for Hornady's 480gr DGX in 45-70. One is a Siamese Mauser, the other a Baikal (Remington) double. I'm concerned about pressure,not velocity. The inntended use is for LARGE feral hogs at 40 yards or less. Any thoughts?

I would be worried about pressure too.
Get a load meant for the Mauser loaded into the double and you might have a problem. And it will be right in front of your face.