That's the approximate position I put my ABS unit.spot check me please: Making an ABS pump bracket. Mounting it next to Breeze forward battery box. 4.6l with hydro boost. Donor radiator and metal corrugated hoses. Wire harness has enough slack to reach. It's 4 channel so I need to buy different brake lines anyways. I don't see any obvious conflicts. How about you?
As for the rear tires with the stock 04 rear end (had a 2004 GT donor) which is the widest, I put 315's by having teamIII make me up some rims with the stock front offset and they fit perfectly. Mine is a mark 3.1 so don't know if a mark IV will still fit. You don't get the deep dish look but get the wide tire inside the fenders.