Clint,try calling mike at Redline outboard services in abingdon,oxon.Tel 01235 521562.I don't think he has a website so the phone is the best way.He has been dealing with outboards since the '70s and specialises in parts for old out boards,keeping many parts on the shelf.If he hasn't got it he should know where to get it as he often supplies other outboard repairers with parts.It has been said that what he doesn't know isn't worth knowing!
He can also do mail order or send you the part you need when it arrives at his place.
I recommend Mike, as my thing is fixing old out boards and he has always found me the parts i needed.