Redneck solution No 1.
I started with a standard XJ40 injection manifold welded up the injection ports, removed the throttle body, fabricated a mount for a Weber 38DGAS 3lt carb so suit the existing manifold and bolted it in place.
It's a bit crude but should work.
As a back-up I have also cut-up another XJ40 manifold.
The pair of XS750 bike carbs where joined together using a little aluminium light angle across the top of carb 3 and carb 4 plus a strip of 30x3 flat bar tack welded to the original carb support bracket. To my surprise this assembly weighs in at over 5kgs!!
I spaced them so carb 2 and carb 4 would line-up with port 2 and port 4.
I will now order the tube and will complete the manifold at a later date.