Bill,
Going back to answer your original post, most folks seem to agree that Oxen blocks are not the way to go. Nothing more need be said.

The Ratchamatic IS the way to go. The problem you are having is having an easy way to cleat. So, the absolutely best answer is to use the Harken 2628 (a Ratchamatic, with cleat and becket.)
This gives a ratchet while sheeting and cleating. And the beauty is that when tacking or jibing, the sheet has no drag and will come across to the other side without fouling.
This system has kept many a bad tack from happening. I love the system.
We do carry the blocks on this site at http://store.catsailor.com/tek9.asp?pg=products&specific=jmmrdpdmp8

No need for self-tacking and all the hassles you will encounter to set it up, not to mention the less sail area.
The reason the pre-Nacra6.0NA was not popular was because of the self-tacking jib -- not nearly the power, balance or control of the NA.

Good luck,
Rick