I have a pretty cool spreadsheet I set up that will help with axle lengths and wheel backspace. Minitubbed or not, spring relocation both shackle and into frame. It's for A body cars, 67-75. I didn't have a early A to measure off of.
Thank You for responding, I just can’t find much information for 63’s...I have to find out which 8.75 will work for my swap and also how many splines it should have.