I've now successfully completed the sub-frame conversion. It's not quite as straightforward as made out. Huge thanks to Paul at: 

P C Auto's Jaguar Specialist, Aldridge, Nr Walsall for committing to, and completing this conversion.

 

Definitive XK X150 to F-Type Front Sub-Frame Replacement

• Locate an F-Type 3.0/5.0. The series one, RWD, Hydraulic Steering. The sub-frame is a direct fit. P/N EX53-5019-AH
• You will also need the rear lower control arms and headlamp auto height adjuster mountings and sensors.
• The lower control arms from the XK are too wide at the bushes, to fit the F-Type apertures. Replace with the correct F-Type lower (rear control arms inc. bushes). Luckily my sub-frame came with control arms.
• The lower front Banana control arms from the XK DO fit the F-Type Sub-frame perfectly.
• The headlight automatic height adjustment sensors and mounting plates are required from the F-Type sub-frame due to the mounting orientation being 90’ out.  
• The original anti-roll/sway bar and steering rack fit the sub-frame perfectly.
• Keep the original XK headlight height sensors just in case the F-Type ones have a different connector. I had to retrofit my original R/H sensor.
• The Oil Cooler mounting tray will not fit the F-Type sub-frame, so discard. The oil cooler will screw into the sub-frame rear mounting hole and the front will slot under the retaining tongues. Fit a rubber bush between the cooler and tongues to prevent movement and rattling.
• Set the geometry as best by eye.
• You WILL require a full laser Castor, Camber, Toe/track check/set up.

My car handles and drives better than before, this could be due to it needing a laser set up anyway. 

Thanks for posting this. I was under the impression that it was a straight swap. Nice to know on advance what replacement parts I will need. ( bought at a reasonable cost!) Now I just need to see if my local jag specialist is willing to do the swap without charging a fortune! 

Thanks again, AL