I made three bad mistakes while building pit. Seat, once assembled as instructions indicate, won’t clear control cables, as cables run between seat and seat frame. I chopped out the horizontal supports on my seat to clear, since I had added cables first.
Rear plywood bulkhead needs to be more or less completely vertical, and engages a notch in floor if done properly. I glued bottom of tanks behind bulkhead to shelf behind floor, kicking out the bottom of the bulkhead forward ever so slightly. This does not help at all with the other fit issues I had.
In my zeal to close up fuselage halves, I neglected to add oil tank/instrumentation assembly, which is captured between two tabs on fuselage side frames. After grinding tabs down some, I was able to spring fuselage open enough to capture the oil tank assembly.