engine clearance issue

[1972BackInBlackC10]

i just installed my motor and trans into my 67 chev and theres almost no clearance inbetween the valve covers and the firewall, im worried that under torque the motor will move and the valve covers will hit the firewall

theres pics below you can fit maybe a quarter inbetween them thats how much room there is, will i need to move my motor ahead? how can i do this? im using the stock motor mounts in the stock location the trans is also bolted to the crossmember, i cant put smaller valve covers on as it needs the clearance for the rockers, i can get more or specific pictures if anyone needs them