Went to the airport and picked up some AN6-25 bolts for lower center mounting through the firewal The -24's were a bit short due to the washer I had to use to shim the engine mount. The -25's were perfect length, I torqued all bolts to 180 in lbs and cottor pinned. I deburred the holes in the upper firewall where the skin attaches. Still checking for anything that needs to be done before mounting the engine on Saturday.