Eddy 1405 tuning advice

Got headers?
What's yur Cruise Rpm, and cruise-timing, all in?

My 360, when it had the 270/276/110 cam in it, cruised on the transfers plus mixture screws. It didn't matter what mains I put in it, it just kept on motoring ....... until I accidently got some heavily alcholized gas......... but that's another story, lol.
Make sure your Secondarys are closed while cruising.
In my engine, that 270 cam did not require much Idle-air bypass; I think I drilled the Primary throttles blades, one each of 1/16 inch holes.
I do think tho that transfer slots could be just barely visibly taller than wide but you can figure that out by how far open the mixture screws are. If they are more than 2.5 turns out, then yeah, the slots could be taller, This will change slightly with Idle-timing; but IMO
15degrees is already pushing the upper limit, as evidenced by the 125 rpm drop, going into gear. Which is not all that bad, just more than I like to see. By retarding the idle-timing, the idle power will go down, and the rpm-drop should be reduced. If you are Ok with it where it is, leave the idle-timing alone.
Just so you know, I idled my 360 at 12 degrees......... most of the time. But because my car is a manual trans, to drive really slow in first gear, I found that she was well able to pull herself around the parking lot at 5* advance, which was 4mph at 550 rpm, yes at 5* advance. 500 was 3.5 mph....... walking speed for young folk.