Re: a hole in float--no hole. If all else is good, & it had one, float would fill w/fuel, drop to bottom of tank, and read "Empty" all the time.
Re: sputtering when turning 1 direction--You already mentioned using a vented cap--quick, cheap, & good suggestion! Next, if it has one, I'd replace short flex fuel line connecting steel line from tank to rear of fuel pump: like me, they will collapse when they get a bit of age on them.
**During hard right, engine prolly stays pretty much down on motor supports, as engine torques left very seldom[exc. in reverse, keeping pass. side support from wearing fast], whereas it torques hard to right every time you accelerate & thus wears out driver side support first; this worn support lets engine rotate hard on left turns, possibly helping flex line to begin its kink/collapse.
More likely, imo: then, I'd carefully set the float level to correct specs per the number on your carb and kit/float used. That level is critical on a q'jet., & I'd suspect it to be shutting your needle-and-seat while a bit low. Those are great carbs, when right--else GM wouldn't have used them for so long and on so many applications. May take a time or two, but you can get it adjusted properly.
Sam