I'm assuming the carb is new
It's a very good size for a .030 SB Ford. It IS a vacuum secondary carb. It is an emissions carb (kinda). It is NOT anything more then close to being street ready in that you may have to make jet, discharge nozzles or even power valve changes to make it 'right' for your engine/camshaft(whatever a 'custom' camshaft is). Then of course is the timing, curve and initial, and is it set correctly which can show the same effects of a lean condition, i.e. blued and possibly glowing headers.
It's dam' poor dyno shop that can't diagnose and make these changes. I would run, not walk to that shop, pay them and leave - forever - and at the next shop, I would sit and watch