Surge At Part Throttle

Have you discussed that with the shop tuning it? What did they suggest.

What's your complaint about how they've tuned it? To some degree there's only so much they can do to overcome the limitations of your hardware. For example if your header runners are too big you're going to lose some torque. If you're experiencing surging it's possible it's tuned a little lean at low-load cruise RPM's. They should be easily able to adjust that for you. It's actually an area on the dyno that's a little difficult to simulate, sometimes you're better off using a tuner that studies your datalogs than just a dyno session (where they understandably often focus on peak power and idle and often don't spend a lot of time on the in-between).

Personally I'd never go backwards to a carb if I could avoid it. Tons of expense for a poorer experience, in my experience. If you can tune a carb and ignition the old-fashioned way, you can easily do it yourself with Moates / Tweecer. Lots of guys here to help you if you get in over your head. There's also a few guys who remotely tune professionally who could probably get you fixed up.