Only A-bodies had axles that will fit an A-body housing without shortening. If you want big bolt pattern 7.25" axles, you'll need to get them out of a BBP A body with a 7.25
The F body axles are longer. You can swap the entire housing over, they're only a little over an inch wider flange to flange, so you only need an extra 1/2" per side of clearance...
For that matter, grab an 8 1/4 out of an F body and use that.