.5 hrs. deciding I wasn't in the mood today to work on it too much...  Mostly for the reasons below.

The holes between the skins on firewall seem to be misaligned for the bottom few holes.

Bottom view.

Gathering some parts, including the two trapezoidal parts on the right which will need to be installed into the rear fuselage (requires drilling out some rivets).  These parts are part of the modification to move the seats more forward.  I wasn't going to do this if I was using the 915 (heavier), but if I go with the 914 or modified 912, then the seats need to be in the forward position.

Some rivets in there that can only be done with the side skins out of the way...