I have to be honest. When I read "street", "12:1 compression", and "4.56 gears" I had to laugh. There is nothing street about either of them, let alone both. You would be building a race car to drive on the street. The good thing is there are no rules on the street. I, like you, do love high winding small blocks better than anything, and I have anything in the shop except for a /6 or a 2nd gen Hemi. To me the "street" limiting factors are the valve train at 6,500 to 7,000 rpm, compression ratio about 9.0:1 to run pump gas, factory exhaust manifolds, and gears to run 75 to 80 mph all day long. I'll be building a "cheapie" 273 build to replace the 273 Commando in the 66 so I can run 91 to 93 octane gas. But that is me. Good luck and keep us posted.