I ran a 318 with 360 heads and 10.5 compression pistons and a stock 340 cam with rhoades lifters... The larger chamber in the 360 head brought my compression down to 9.2 which was perfect... that combo with a 2.76 gear ran great and got 17.75 MPG highway... Idled at 22.5" vacuum... No need for higher stall converter or gear....