I also would not combine the 2, run them to a pump manifold on their own. Also, I suggest if you are going to add 40 more taps it should be split into 2 lines, 3/16.
The 3/16 lines on flat ground will yield less sap than a proper line system and a sap ladder, it will still yield a decent amount. The loss will be from line friction, but you will get more sap/$ invested than if you used 5/16 and a sap ladder on a 200' long mainline, especially using a ShurFlo.
I have likely 60-75% of my lines on 3/16 and pulling from below the mainline. However I use a mechanical vacuum (generating 26-27" vacuum) and a releaser. A ShurFlo will not do as well, but The vacuum pump and the releaser would add plenty to your cost. My vacuum pump is an antique, a BB4 piston pump, made by Babson Bros, before they became Surge.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.