valve cover clearence on firewall question

[blazer2007]

I,ve just put in a 454 auto in 78 blazer 2 wheel,but my nice new tall valve covers are very close to the firewall.I see the problem with the valve covers as they are square,I have a little more than a 1/4 inch room but I was wondering how much the torque is going to move the engine,is a good 450 hp.I also have the good poly motors mounts and tranny.