Fuselage question

I am preparing to disassemble fuselage for deburring, dimpling etc. my question is riveting the firewall to the forward bottom and side skins. I am lookin at the preview plans to see how the cowl fits to the fuselage, but can't seem to make sense of how the cow fits except for using a hinge. But what does the hinge fit too. What should I rivet on the firewall now?

On my RV-7 (same fuselage dimensions) I have no plans to rivet anything on the firewall flange until I attach the cowling.

Look again. You must fabricate the hinge pieces and spacers to off set the hinges in to provide for the fiberglass cowl thickness. These need to be drilled, deburred and countersunk before riveting them together with the side and bottom skin and firewall. Do make sure to trim the stainless steel firewall edges back before assembly to match the side skins. If you don't it will be very hard to do and protect your nice side skin edge prior to riveting and impossible after.

There are good reasons to do before cowl fitting. Attaching the hinges eliminates clecos in the way and securely fits everything for a good fit and alignment. The cowl part of the hinge provides support and positioning for cutting and fitting the cowl. I've done three cowls that way so far.

I agree it's a little confusing about what exactly needs to be done while attaching the forward side skins. I'm in process at that stage. So far I've left some of the forward rivets out in addition to the firewall rivets. I was trying to figure out about firewall sealant too.