ours goes in tomorrow for our dealers custom version of that package. stage 4 head work, TR-590 cams, high compression pistons, pushrods, V&H Dresser Duals and Hi Outputs and tuner with custom map.
i'm holding off on the 58mm TB, Heavy Breather and injector upgrade.............trying to stay rider and touring friendly... 
I agree with Tabatha in that the 58mm would still be user friendly and very driveable.
For some of us old riders, we've been around the block a few times with cars and BIG carbs, or BIG carbs on bikes. With a carb you are very limited to airflow speed and the mixing of the fuel and air. Bigger is NOT always better. Too large of a venturi and the air speed drops and the mixing goes south really quick, very poor performance and very poor mileage. But it did sound cool when you said your 283 had a 750 dual pumper. It ran like chit, but bench racing was great.
When I was going through my research for my '55 Nomad Gasser project with a 540" 660 hp bbc, I was looking for "old school" looks. I really wanted to go with a new tech fuel system but with with old style 8-stack fuel injection intake. Very cool looking. If you've never seen one it's worth looking up on the net for some pictures.
But I digress... When checking with some of the conversion guys I told them that I can only find large bore venturi 8-stack intake and injectors, like 1.75" to 2.2" and was very afraid of the too big factor, like on carbs. They quickly explained that the motor only uses what air it needs and will not stumble at part throttle, like in town driving in traffic. The electronics controls the fuel through the direct runner added injectors. But at WOT it will produce more power, again while maintaining a very comfortable driveability at the lower throttle setting.
Yes, there is a limit to how big you can go on a TB and "some" sizing is necessary. My guess is that a 58mm is still way below any major problems with driveability.
I did a quick comparison on the Victory dual TB setup for a 106" motor and compared that to a 58mm TB for HD. The Victory has 4.98" surface area in the TB compared to 4.08" of surface area in a 58mm TB.
I would definitely go with the 58mm if I got into my motor at all, like adding a cam etc. Just to put on a 58mm to my stock SERG would not be worth the effort for what minor hp gains I might get. But I'm sure it would still run fine and handle quite nicely around town.
I'm sure others have more technical advice or comments, these are just my findings from a few years ago. I'm always trying to learn more and I'm very open to new info or even being corrected in my thoughts.
Dan