I started out by locating the air conditioning hose pass-through for the firewall. I roughly hung the engine mount using drill bits as pins in the pre-drilled holes in the firewall. Once I had determined the location, I used the paper template that came with the fitting and a punch to transfer the hole centers to the firewall. Then I used a lot of cutting oil and a unibit to make the holes. I had to use a dremel tool to deburr and then I cleaned the cutting oil off with mineral spirits before attaching the fitting to the firewall.
Next I put the bend in the right-hand skin the same way I did the left skin yesterday. When the bend was done, I clecoed the lower channel and clip to it and fitted it to the fuselage structure. Starting with the upper weldment at the firewall, I match-drilled everything. I used a wood block (see Image 2 where I clamped the block for drilling) to push the weldment against the skin. Since there was no convenient way to clamp the lower weldment, I left it undrilled until I can get some help. I stopped once all the #40 and #30 holes in the skin were match-drilled but before the #12 holes or any of the holes holding the underlying structure together.