Wild guess #2: min Tarcles will be about 352, and this solution will place 1st. 

Clean 4-arm 13R. I do not see how this solution gets beaten. 5-arm 10R is not happening, and I think a 3-arm 18R or 2-arm 27R would require some Blood Staunching Powder TI level shit. 

However, Arms 3 and 4 kinda need to do 1.5 arms' work to keep up with the sauce; I have a 20R 3-arm solve without arm 4. That may be this solve's downfall, but I cannot imagine anything more efficient.

Found the secret sauce completely by accident - I was sitting at about 500 Tarcles not feeling great about my solve, with an every-4 mechanism that took 3 arms to make the monomer. Then I realised that I could combine the arms that moved the mors and the earth, leading to my score immediately nosediving to 400 and me now having an every-3 mechanism taking only 2 arms.