If I understand your problem correctly, the mainsail boom of your Nauticat 33, hits the forward starboard mizzen stay, but clears the forward portside mizzen stay by 1".
It is possible that your mainmast may need some fine tuning. Perhaps the forward port stay is over tightened, resulting in an excessive mast lean towards the forward port quarter. This would cause the boom to swing in an arc not parallel with the deck . . . boom end higher to starboard aft quarter than port. Hence, the boom end hits the forward starboard mizzen stay, but clears the port stay.
Another scenario, is that the forward starboard mizzen stay is positioned incorrectly on the pilothouse roof. I know the stays of both mizzen & main masts of my Nauticat 33 are equally positioned, with no boom swing interference. Siltala Yachts produces the best built motorsailers in the world in compliance with the LLoyd''s Register of Shipping, so it is highly unlikely the NC33 would pass their strict standards in that condition.
If it would help, I could email copies of my sail & deck plans and/or digital photos for comparison with your boat.