I am also building a P-47 with a Supertigre .75 with robart retracts. I did not buy the TF in cowl muffler due to the header not being available. I instead bought the slimline sportscale muffler. I am going to mount the engine vertically with the engine head and muffler end pointed toward the bottom so the top and sides of the cowl are not cut into. My question is do I have to do something special while mounting the engine this way or do i just keep the engine centered with the 4 indentions in the firewall and mount it vertically?