Love that this build is going again!!

I would not have the fill line there permanently as I feel it would add too much clutter - plus I am not a big fan of it being shared between the two loops. I mean why go to all the trouble of two seperate loops only to have them connected at the res? Perhaps a quick disconnect type fitting on your bracket that is attached to the rad as well as one for each res for quick and easy filling - which would also give you to flexibility of only filling one loop at a time option as well. my