Just make sure you use a FORGED axel! You can have your axel dropped.296 V8 on here or Joes speed shop or Nostalgia Sid.
Depends on the axle and how you mount the spring. A lot of after market axles are 37-40 types and the bungs for the spring pearch are too wide for an A spring, but if you mount the spring behind and fab mounts on your bones it could be done. I don't think that anyone makes an A width drop axle if that is what you are asking.
Call Joe (OkieJoe? i believe is his hamb name) at Joes' Speed Shop in Oklahoma. He will fix you up with an original model 'A' axle, dropped to your needs and drilled etc if you want for very reasonable price. That is all he does and has been doing it forever. Then you won't have to worry about getting some chinese junk.
Most new axles use there own spring. The makers have narrowed the dimension between perch’s. Resulting in the need for a narrower spring.
I just went out and measured my SoCal dropped axle and it's 34 center to center on the pearches and 47 center to center on the pins. What I thought (and it may still be) was a Model A that I have was a bit over 36 on the perches and a rough 49-1/2 on the pins. With backing plates and the mechanical brakes that is hard to tell at 7:50 in the am.