Brother of The Benz, Dave
Sorry I didn't read your thread sooner and sorry your child needs head work.
Adsit Company, Inc. @ 1-800-521-7656 offers cylinderheads for the 300E at $895.00 exchange with a $500.00 core charge pending the return and rebuildable condition of your exchanged cylinderhead.
Good luck with what ever method you chose, but this sounds very good to me and should the time occur this is my route.
Happy Trails Beep Beep from The Spiderman in Houston!!!