It won't matter where you set the floats if you're running two B's on a 235- - - -it's going to run lousy regardless of where you set the floats. If you insist on running that setup, set the float level as high as possible without gas dribbling out of the venturis with the engine idling. Set the float drop so it keeps the float from bottoming out against the bottom of the float bowl. Keep a good fire extinguisher handy, as the frequent backfires you're going to encounter will set the carbs on fire on a regular basis.

If you want that setup to run somewhere close to right, find a matched pair of Carter carbs for a 216, rebuild them both to exactly the same specifications, and modify the intake manifold stud spacing for the narrower throttle body bolt pattern.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!