I run taylor 8.8 wires, work great with the 5.0 and careful routing around the headers. I take my wires to the fender skirt instead of along the valve cover.
You should check your transmission mount, the factory mount SUCKS and will allow lots of movement, replace the engine mounts and no mention of the trans mount? I would replace that sucker ASAP
Remflex gaskets are a must with headers on this 302
You can run a smaller booster if needed.... I have used 8" and 9" boosters from a Mustang II on these explorers/rangers to gain more clearance, they have the same boost ability, bolt on, and are much smaller diameter