I did this a few months ago! I went to PK Racing, and Chris is an instructor for Serotta's fit school. I originally went with the idea of getting a new brevet bike. My bike is great, but after 200 miles, I find myself on the tops a lot and felt the fit could be tweaked. also, I tend to get pain in my right lower back down my leg.

I spent 3 hours with Chris and he did the things you described and tweaked my bike a lot - lowered seat, changed stem, changed cleat location, etc.

I am still not able to ride outdoors til January (unrelated medical issue). but I feel a lot more power and openness (thats the only word I can think of) during my spinerval workouts.

he gave me a great printout showing how to measure and set up existing or new bikes and measurements for a custom bike when I eventually go this route.

it was expensive ($300) but worth it in my mind.