Thanks for the comments, I'm aiming for a base pitch (chamber tonic) of C a=440, do you have any pictures of your own ocarinas? Ocarinas can be played as both a transposing or non-transposing instrument, the note intervals are generally the same.
The base pitch of an ocarina is primarily determined by chamber volume and blowing pressure, the former must be sized so that the ocarina plays in pitch without excessive breath. It is possible to vary this somewhat with sound hole size, or by drilling a tuning hole, however they do reduce the maximum achievable range and weaken the high notes. Not good for 11/12 hole ocarinas.
The biggest problem is that clay shrinks which causes the pitch to increase, you have to vary the wall thickness in the mold so that its tuned flat such that shrinkage brings it to the correct pitch. It's just trial and error.
I am aware of that book and have heard good things about it, however I have not read it as it's not available in the UK and international shipping and import tax gets very expensive. If there was a PDF version available, I wold buy it instantly.
Actually I have just finished writing a book specifically about the issues of ocarina making, in which I have made a lot of effort to highlight the biggest stumbling blocks and explain why things are done on a technical level. It has the most detailed explanation of ocarina voicing and tuning that I'm aware of, most of which I figured out myself by considering how airflows interact with the chamber (basically running fluid simulations in my head, then testing in reality). It can be found in ebook format(pdf) from https://ocarinamaking.com and in print from http://www.lulu.com/...t-20121385.html