Apparently need to replace the Worn Front Springs,( Perf. Suspension Pkg.) as noted on Factory build sheet... The L.F. measures 14 3/4" and R.F. is 15". The Welsh Poly Mounts do not appear to be compressed. Looks like the choice is clear, but?? New Springs for a Coupe are scarce. I'M checking some UK suppliers and looking USA also. Do not want to use lowering springs as these defeat my purpose. Since only about 20% of XK8's were coupes, I can see economically why replacement spring may not be plentiful. Does anyone know how to secure the spring info such as Rate, Load, and other related info. Maybe custom wound set by Easton- Detroit Spring. I'm kinda lost, but would consider a convertible spring if slightly different. Listed weight difference (Cpe. vs Vert.) is 260#. Open to your ideas and suggestions regarding comparable front springs. HELP!
SNG Barrett advised A/M NLA. Same for some others.

Call Detroit Axle and ask if they can help you or know someone who can. (888) 583-0255.

I would also call FCP Euro. (877) 634-0063.

Have you talked with Welsh Enterprises?

Try DCR - think he's out of Scotland - shows OEM for coupe/convertible as well as lowering - https://www.xk8-parts.com/2016/10/ja...-gallery-page/

New pair of Suplex springs ordered from vendor in UK to replace my Orange stripe JLM20711. Noted some has negative feedback on the Suplex but others and a Jaguar dealer I use for parts advised they provided them w/o problems. Will report back when install is complete and a few miles. $230 Incl. S&H. Not cheap but less than OEM by $300 which are NLA. :-)

UPDATE NEW FRONT SPRINGS-- A/M (aftermarket)
Completed install yesterday using the Remove Fender Liner Procedure. Much less problematic than the removal of the upper control arm at the rear bolt and spacers. Had a local shop install new springs on the 20k shocks done earlier when the Welsh Poly upper mounts and spring assisters were changed. Prior to change, the Right side sat at 15" and the Left sat at 14 3/4" with the Poly mounts. After replacement and sitting overnight; the Right side sat at 16" and Left side sat at 15 3/4". The new springs made a 1" difference. The Poly Mounts were still in excellent condition and showed no sign of collapse or wear. The A/M springs were Suplex from a Vendor in UK. Local sources were unable to help and the OEM are NLA. The part # for coupe was AC13041. Vert has a different part # AC13040 Frt. Cost on pair of these springs was $165 + $66 S&H. Ordered on Sat. and arrived Tue. at 12 Noon by Fed-Ex. I know the right side is a bit higher but perhaps they will settle after some time and mileage. Vendor was Victoria Auto Parts, they have a presence on E-Bay US & UK. They were very helpful and responsive to my questions regarding these springs. Suplex is German Company and has a branch in UK. . Will report back after some time and miles accumulate.