The platinum plugs originally used for the Optimax were very expensive. Now they use an iridium plug that is cheaper and back fits all Opti's.
There's some good news for the Opti!!...Nick had a pair of 200s on Phat Kat...probably had 2,000 hrs on 'em by time he died...gobbs of power across the curve and fuel economy w/out equal...2 hrs to Gulf Stream, troll all day and 2 hrs back at 26 kts...on 90 gals fuel...nobody could match that back then...