Cruise friendly low 12's with a 340 Dart

The "Basic 4 inch kit" is indeed a ref to the stroker route.

I'm with 3404spdVal on the spacer for the carb issue, your not looseing power. It's a non issue item.

On the spreadbore carb, the T-Q is a bit of a trick to get right and parts for and the Q-J is also in the same trick to get right, but parts are easier to get.
Bottom line is what ever carb your OK in fussing with is what you should use.