Tonight I opened up the slots in the F-706, F-707 and F-708 bulkheads slightly to clear the left longeron. I used several pieces of scrap angle clamped together to simulate the longeron so I wouldn't have to repeatedly remove and install the longeron. I still have to remove about 1/32 inch or so from the aft end of the horizontal leg of the right longeron to ensure the vertical stabilizer spar will fit flush to the F-712 bulkhead.