I've been researching the MTB FD vs RB FD and brifters thing and think you might be best served by just swapping out the FD for a road specific triple version just to get the best results. When I was considering doing a drop bar conversion that was what I was going to do but I came across a road bike to build up and decided to keep my flatbar on my Schwinn Crosscut.
The road bike needed a new crankset due to the original being damaged and I ended up putting a 28/38/48 Biopace crankset on it and am using a Shimano Claris FD-2403 with friction shifters and everything is working very smoothly. I will eventually go with brifters on this build so I'm looking forward to a report on your results. The only issue setting up FD's with Biopace rings is making sure the middle ring isn't rubbing the back plate of the derailleur when in the big ring, you basically have to ignore the old 1mm rule of thumb and set the FD as high up the seatpost as needed to clear the Biopace rings in all positions.