Very nice work. Only draw back to that solution is it goes against the (current) filter clearance rule. Basic rule is that you should have, as a minimum, the same internal clearance as the throat ID. The 550 carbs are 35mm, and the filter (45mm - 10mm filter material) just meets this. To get it to squeeze in, I drill the holes above the centre line (drops filter slightly), and modified the back plate mounting point on the stacks from stock. The result adds just enough horizontal clearance to allow for a 45mm filter (without crushing the support wire).
All that said, I will be interested to hear how your revision works.
As for a next order. The price will have to go up by $25/kit, as all my costs have increased. The deposit amount will also change from $60 to $100. So I need to know how many are still interested. As soon as I get 8 firm orders (with deposits), I can proceed. Currently all my available funds are going into getting my vintage sidecar ready for this season's racing. So unfortunately, I can't fund this out of personal $'s anymore. Also I will only be offering kits, no stacks only in the future.