Help me design a throttle linkage for this beast

I'm trying to come up with a homemade, low budget, progressive throttle linkage for a triple deuce set up on a Chevy 250 straight six. I'm trying to keep it as simple as possible and use rods instead of cables. Carbs are Weber 38 Outlaws. Any suggestions are appreciated, Thanks.

 

What about copying the way a 4 barrels secondary's kick in and use that as your design template. Would be pretty cool I think.

 

That's kinda how I'm thinking, just haven't figured out the geometry yet.