Hi HRH...
not sure about the door diaginals either, I will check the spec book a little later today for you...
25.4 spec is for round tube chassis, you will need to go with 25.5 spec for what you are doing.
from what I see here, you will need funny car cage, roof diaginal, some gussets from main hoop to windshield bars, and a few floor diaginals to meet the spec.
It is best to spend the 35 bucks and order them from sfi, best 35 bucks you will spend on your racecar.
Otherwise, everything looks good from what I can tell....
ed