Shorten the hex bar and re thread as needed, being sure that at full WOT you do not over center and cause the throttles to not return. (Maybe do a dummy run on some scrap material before modifying to work out what works best)
This will effectively rotate the pulley around to a more...
In my experience with both Borla and the Speedmaster copies of Borla 8 stack, shortening the drive links and re clocking the bell crank to a better angle will significantly help with both initial pedal pressure to open throttle progressively and also help to return to a closed position.
Maybe something like these screw in units https://www.ebay.com.au/itm/Threaded-Fuel-Injectors-1000cc-screw-in-auxiliary-/162662546656 simplifies it.
Alternatively, a small manifold inside the plenum with hose tail end injectors like this could work
Peter, It almost looks like that intake can be mounted up the other way so the injection is down flow (IE injecting above and into the butterfly) my supervee kugelfischer mechanical injection is similar with injectors before butterfly (pointing in flow direction)
I have successfully used a couple of the Speed Master systems on a couple of customers Cobras. These are a Chinese manufactured knock off of the Inglese / Borla inside mounted fuel rail systems. They work OK but quality can vary batch to batch so you have to be careful.
I had an Inglese / Borla...
A lot of people have used this unit in Australia. It is the old DC & O manufactured unit and has always been good quality. I believe EFI hardware in Melbourne do the machining and assembly on them which is great as they are a really reputable company.
The US guys have used the same system...