I like the arky head myself and I make them on the poison swing head. The blade thumps the head good on the arky to the point it's wearing down the lead.
My brush hog mold has one cavity on each side of the spru. Single cavities work good. I've done it on 4 cavity molds but ya have to use a old piece of spru to block some cavities.
One more thing you usually have to make the outside color quite a bit darker than normal because it's just a skin coat and the inside color will come through
Don't know the exact temps but I like the color I'm pouring a little thicker so it doesn't just run into the cavities. I do this with a two cavity. It has one cavity on each side of the spru.
Fshnh2 I mostly use the 1/4 oz. with a size 3 willow. I run a Do-It 3.75" essential series swimbait on it or a 3.8" keitech variation on there. I mostly fish it along weed lines and lay downs.
I have the top inject 639 and for the life of me I cannot get the ribs to fill out right. I have tried heating the mold, shooting the plastic hotter and cooler, and holding pressure for various amounts of time, and injecting at different speeds.
I use both. I made my plate so I get a half out of each side of the mold. I use the plate mainly to save plastic. Some molds though require the dual injector to do laminates. Like stated it is faster.
I think you injected the second color to fast and the second color lifted and shot around the half already in the mold. That would explain the lack rings and the black being flat.