I can't say for certain, but IIRC the P heads don't work with any cast exhaust manifold. Although they would bolt to the head there isn't enough clearence for the spark plug. The Explorers (which these heads were used on as oem) came with tubular manifolds.
Works fine. I've got that exact combo on the 351W in my 68 Cougar. Couple of the driver's side plugs (back 2) are tough to get to, but not horrible. A good set of 90 or even better, variable angle plug wires and you are good to go.