Holley carb ?

That's a Thermoquad replacement 650 Holley. They also made a Quadrajet replacement that was basically the same except for the linkage. I had one (the Q-jet replacement version) about 25 yrs. ago on a Chevy 350 that ran great and got decent fuel mileage. As long as it's rebuildable it should work fine. Check the throttle shafts for slop. If their ok it's probably ok to rebuild as long as no water ever got in it and oxidized the innards. What's the list #? I think mine was a 6231 or something like that.

Why not use the 750 vac sec in the background? It looks fairly clean.