That motor and exhaust is a credit to you, how did you find the fitment. Without talking to anyone with a right hand drive car i am unsure if any USA headers will clear my steering box, now i don’t have an early XK-XP, i have a 67 XR so factory 289 windsor was an option, any small block will go in, mate had a stroker clevo with pacemaker 2” pipes so they are wide in the bay, i need someone to measure from a reference point on the engine to the most extreme pipe edge to see whether a stainless set will fit.