This is one of those nasty little tasks that takes more time to figure out how to match a curve, than it does to actually cut and install the parts.
1. Measured curve that gusset must match. 2. Cut cardboard template matching curve, and fit check on both port and stbd sides. 3. Trimmed gussets to match curve. 4. Clamped stbd gusset in place, and marked best rivet locations. 5. Removed gusset, punched rivet locaitons, and drilled with #40 bit. 6. Clamped stbd gusset back in place. 7. Back drilled and clecoed rivet holes with #40 bit. 8. Opened holes with #30 bit for A4 rivets. 9. Repeated steps 4-8 for port gusset.