Look at the rotor arm, does it have a sprung loaded movement limiter built in ?, NO SIERRA COSSIE EVER DID, have a rev limited rotor arm, so if it's wrong change it.
Frankly speaking I can't see ANY petrol car engine being limited to 4500rpm.
The fact it revs clean stood still means NOTHING, it could still be ignition, or fuelling, my moneys on fuelling, with the flames, this is indicative of very rich running.
The most obvious thing has been overlooked, the rotor arm/dizzy doesn't just deliver sparks where needed, the dizzy also has a phase sensor, if this is out, it goes into melt down fuelling wise being monstrously rich.
Line the cams up, with the LUG nearest the V in the pulley, NOT the v mark, then check the rotor arm is 100% centred with the scribed line on the dizzy body visible under the heat shield that sits on top of the dizzy body and gets clamped by the cap.
Have you defo lined up cam timing with LUG nearest the V groove and NOT the V groove itself ?.
Ford quote max power of 204PS(not bhp) at 6000rpm, taken directly from my ford sales brochure, but reality is different, taken directly from my rolling road printouts with STD cams, head etc peak was on mine last time 6439, but previously on GGR chip(and crappy L6 ecu) peak bhp was 5591rpm, most I've seem were nearer 6000 peak bhp, but that's not the issue anyway.
tabetha