Your experience differs greatly from what i have ever seen. Had a bone stock 70 340 Duster that needed way more than a cam and more gear to get into the 12’s........ way more. Your talking a car picking up a couple of seconds in ET. Great results friend
But its way off from anything like that i have ever experienced. I needed headers, and other boltons to get there, think i even had to use aftermarket convertor.
My little brother has a 71 Dart with 10.5 compression 340. 202 heads, comp flat tappet cam, 3500 convertor, holley 750, aluminum intake, 4.11 gears, headers, and it runs 12.70’s in good air. Well sorted out little combo