You should be able to pull the axles and reinstall them without changing the seals. That's not to say that you can't damage the seals when you pull the axles, but if everything goes smoothly it should be fine.
I think A8000 is just the blank for the axle. It specifies the material, not the dimensions which are machined to order. The 9400M bearing is a green bearing set up. The green bearings don't use a thrust block set up like the stock tapered bearings do, so, the axles can be longer. Moser lists all the A-body axles on their website as 28". Moser also sells those axles in 3 variations- for A-body brakes (SBP and SBP flange offset), A-body brakes with re-drilled drums (BBP and SBP axle flange offset) and for BBP brakes (BBP and BBP axle flange offset).
So, all I can tell you is only one set of the brakes you have will actually fit. If the brakes on the 8 3/4 were 10x1.75", the drums fit and no weird spacers were used anywhere, you have a SBP axle flange offset. If that's true, the BBP brakes off the 7.25" won't fit. Is there a part number on that receipt? Should look like A30-CST-A4 (or A30-CST-A45, or A30-CST-AB45).
