[hatzie]

The 9635 & 9635S Competition AFB were Carter manufactured 650CFM Aluminum Four Barrel carbs with GM Linkage, Electric Choke, and Emissions Calibration. The 9635 is physically the same carb as the 9625 AFB with the addition of an EGR port to make it more emissions friendly.
The 9635SA is a 9635S made after the Carter bankruptcy... probably by Federal Mogul. I would guess that the original Carter rebuild parts will interchange. Metering rods and vacuum piston springs for some Carter one, two, and four barrel carbs can sometimes get a little dicey to find. The 9000 series should be easier because they are not 50 years old.

I took the easy route on one of my projects and don't regret it. I used a stock Chrysler Rochester Quadrajet and spreadbore manifold off an 80's Dodge W200 with a 7.4L to replace the squarebore Carter AVS 4638 on the B383 in my 1969 Polara 500. The metering rods and mating jets in the original 1969 Carter AVS were visibly worn out and close to impossible to find. The Rochester was much easier to rebuild, much easier on fuel, and isn't so cold blooded.

Since this is not an original piece I'd get a rebuilt Rochester and manifold or a new squarebore Holley or Edelbrock carb to replace it. The Holley and Edelbrock squarebore carbs will fit your existing manifold but you'll have to tune em.