I mounted the firewall using the method outlined in the new Quickbuild fuselage manual. The only thing not covered was that the top motor mount hole needs to be drilled out to 3/8 inch if you are going to put a Lycoming 540 in. The kit comes drilled out to 5/16 on the top hole, which apparently works for Lycoming 360's and so forth.
Clamped in place, 1 bolt thru.
An "aircraft drill bit" and right angle drill helps.