[LS short box]

I've done a number of LS swaps. Only one that didn't get a chassis dyno tune was a stock crate LS1 I put in a 71 Corvette. I did a mail order tune and it ran great.
I've never rebuilt a LS harness. I buy the ECM and harness from one source with a base tune. Good enough to get you to the dyno tuner and in my case always on a trailer.
In the MPLS area it's going to be $700-$900 depending on your combo. That includes a road test to check shift points/converter lock up if its an auto. Also check speedo.
Typically I'm at their door step at 8AM and then I'm on my way by noon.
Both of the tuners I've used over the years include a "fine tuning" after you have put a few miles on the car.
One thing that drives tuners crazy is the car owner not knowing what the engine combo is so it's more difficult to narrow down the tune.