Recommended 4bbl carb for stock 318

That is exactly why I want the street demon. I do not want to run that stupid spacer.
I think your best choices are a Thermoquad or Quadrajet. If you really want the SD, you can measure or better yet, trace your intake's surface and then compare it to the base of the Street Demon. Then you'll know if an adapter will be needed for the throttles. A little sturdier method than tracing paper is to use thin cardboard and a soft mallet.