I believe all 600 bowls used end hung floats and a tube to transfer fuel from the front bowl to the rear so IMO their not ideal to use on a 750. 750 and 800 base plates use the same diameter butterflies but there were no 800 vacuum secondary carbs that I know of, only double pumpers. Therefore a 800 base plate won't work unless you replace the shafts with vacuum secondary style shafts.

I saw your other question about mixing 3310-1 parts with 3310-5 parts. Depends on what parts your talking about. Mixing parts sometimes works but some times it throws the calibration off so you'll have to do some re-tuning to get it to run right. If your not real familiar with tuning a Holley it may be a challenge.