The port on the ST170 is around 5mm bigger in height (all at the top) than the standard blacktop so unless you enlarge the port in the head there is a large step.

Richard Holdener's book has some RR power run curves for the manifold in both positions (extensively ported head, crower cams, 8.5:1). The long runner maxed at 150bhp, 7,250rpm, short runner 166bhp, 7,800rpm. The power & torque curves crossed at 5,400rpm, wonder why Ford switch it at 6,000rpm ?

Not sure if it will fit if you have a standard blacktop alternator. On the ST170 bracket its about 10mm lower.

Oh, and if you do boost the manifold, I understand that they die quite rapidly........

Martin