hey im playing around with idea's for a new engine in the d100... im wanting to go with a small block either 318 340 or 360... i would like to reuse this demon i have if possible but im not sure what size engine it would be best suited for... im not looking to hot rod just get a good reliable carb for city driving and easy starts

 

You can run that on any motor you want! I have used Holley 2 barrel 500 cfm on numerous builds. Your demon is an excellent carb. I simple terms CFM is strictly a requirement based on fuel / air needs vs. rpm and volume. Even a stock 360 is perfectly fine. If you are keeping the stock cam and exhaust manifolds I see no issues at all. A stock Magnum 318 / 360 small block air filter thru throttle body flowed 560 cfms stock. Your demo will be very snappy in throttle response and should give you nice results.

Search the web on how to read spark plugs for lean conditions and monitor your plugs. Pull them occasionally and read them. Let us know how she runs.