Glad you folks find this interesting. Been doing a little seat of the pants thinking about what bore size will be required to restrict this setup to a usable flow. Feel free to comment on my theories.

I measured the throttle body bores and they all came up within a few thousandths of 1.75 + or - .003. Now is where I have to make some assumptions and yeah I know what happens when you assume.

Holley rates these TB's at 1000 cfm and all the bores are the same, so that must mean that each hole flows 250 cfm.

If I was building this with carbs, I would either use 390 cfm Holleys or 500 cfm AVS Edelbrocks. The Edelbrocks are rated with dry flow and the Holleys are rated with wet flow, so they are most likely fairly close in practical air flow. I'm going to go with 800 total cfm to start with, which I would think is plenty for any 350 that won't see the north side of 6500 rpm. Calculated required air flow for this engine is about 650 cfm. This means I need 100 cfm per bore to get 800 cfm total.

1.75 (existing bore size) works out to 2.4 square inches and 100 cfm is 40% of the existing 250 cfm rating. 40% of 2.4 is .962 square inches. If I round that up to 1 square inch it works out to a bore size of approximately 1.125. This converts to roughly 103 cfm per bore and 824 total.

I'm not sure if the cfm flow scales up or down like I have figured.

Anyone have any thinking on this?