Meanwhile i did a lot of work.... scoop is now model #4 .
With the short trumpets i was not able to get the gasket rubber over them by pushing the scoop down , and i cannot reach in there with a hand. So i had to make the scoop cover also demountable. Finally it works , cosmetic not fully my taste due the many changes but ok , at least i can dyno test it and see if a filter in the front opening has any effect on power.

and by coincidence i found that the gas linkage i made doesn't work well. Idle is OK , i can synchronise, WOT is OK , but progression is not the same .
I pull on both sides , the carb levers go a bit up the first 45 and then again down. My linkage go's up for the driver side carbs but down for the passenger side ! I tried making drawings to find a solution but i'm afraid there is no with this type !

Options were either turn the passenger side carbs so that those levers must be pushed instead of pulled , or work with 2 gears in the middle so that both pull symmetrical.
I opted for the most work ( turning carbs , cutting and rewelding manifolds as nothing is symmetrical ) but in the end gives the most simple and reliable linkage.