I get a different answer:
Now my true flush deck (M20 style) has 31.5" (.8M) of head room, so if I was in the far FAR South I would need to raise the deck 4". The arched Portland, J24.... deck style would meet the .9M (35.43") head room rule.
So all but my configuration would meet the T1 and I would need to make changes to my deck and cockpit. The anarchist in me says "NOT", but I do not race under the AUZ bucket trailer rules. Sad part is all the i550 configurations are built to the same hull form, must be 800 lbs min, limited 175 lbs keel max, and sail area limited by the rig. Therefore all i550 types should have similar performance potential.
(pink is the 1m2 x .9m tall continuous space, so it starts at the top of the (required) bunks and central stringers)
Frankly, without having the entire text of the rules, it is difficult to know who is right and who is wrong here. However, I disagree with SAPOSWIAB that it has to start at the top of the bunks unless, of course, that is what the T1 rules say, because well placed stringers and other supports could be utilized and I can see where the PDX version could very well pass the T1 rule. Or at least come very close to it. If I was in Australia I think I could raise the deck just a couple of inches (maybe 50 to 75 MM) and be able to meet the T1 requirements.
The important thing to remember is that regardless of the rules set used, the hulls are all close enough that the fleet racing, when it happens, will be far more dependent on sailing ability than the deck, rig or other options one can have on their i550.