I have a 78 mh 440 that had a stock smogger intake and thermobog

swaped it for a weiand action plus with a 650cfm carter performance carb

of course shaveing 60 foot of MH,adding the intake carb,striping down a short bed truck adding 3.91sg,manual VB,mono spring with lift bars

it got plenty of torque with a stock 440,i am sure i will get a little better mpgs than that

or try a Q-jet,holley spredbore 650 double pumper thermobog replacement those both worked good on mine when first getting it running