First of all, I LOVE your design and yes, only an inline engine would look good in it.
Secondly, you are correct in assuming that 11:1 CR is going to be too much on the street. I have first hand experience with this as I put a 300 Ford race motor in a '33 Willys coupe. It had Chevy 350 forged pistons with the domes milled at an angle to match the 300 chambers, probably about 11.5:1 CR. I blew two head gaskets trying to run pump gas. Took out the pistons and milled additional off the top and also installed a long duration, high overlap cam. It probably has about 10.5:1 static CR now. Still too high. I have to put a gallon of race gas (110 RON) in the tank with every fillup of 94 Sunoco premium. Goes like stink but given the choice I would rather prefer about 9.2:1 to be able to run pump gas. See if there is enough stock in your pistons to turn some stock off the top - a relatively simple machining procedure.
Thirdly, regarding side draft carbs, check out the sidedraft intake I built for my '30s era champ car project in the 'Ford' section of this BB. Perhaps something like that with 3 SUs would look good, no?
Good luck with your project and keep us updadte.
