Should it be a concern on how the fuel tank on a easy sport 40 fits tight to the bulk heads . Iam thinking it might cause the fuel to foam .

Most arf's today have the bulkhead and firewall cut to hold the tank snug. On the few I have, foaming hasn't been a problem. If your prop is over 12" and or black, make sure it's balanced to help cut down vibration. Packing the tank area with foam seems to have gone the way of the kits.