It really doesn’t matter what you have in the car !! If it runs better with the 650 !! Well it runs better !! Had a friend years ago decided he needed a 850 dp. So he bought one ! The car went from 6:80 1/8 to 7:05 1/8 ! He put his 750 vac sec back on ran 6:80’s again . 62 Chevy 2 383 small block ! Sometimes just leaving the carb alone is worth a lot !! And sometimes trying different things makes your car go faster !!