N.B. The email exchange below may have been edited, e.g. to remove content not essential to the main point(s) or to standardize English spelling/grammar.
I am attempting to reconstruct an orthographicaly consistent, perfect slavonic text of Gospel of John (with correct use of yus, yat' etc.), using for example the Codices Assemanianus, Marianus, Suprasliensis, Zographensis, and the Savvina kniga from http://www.slav.helsinki.fi and other websites. Perhaps someone has done this already? On your website there is a snippet of what I want: http://www.utexas.edu/cola/centers/lrc/ietexts/ocs/ocs-4-X.html
Can you help me construct such a text, or provide a link to such a text if it exists?
Best regards. V.
Thanks so much for your inquiry. The most straightforward answer I can give you is simply that I am presently unaware of any text of the sort you describe. If you do endeavor to reconstruct one yourself, then the manuscripts you listed are where I myself would look first; so in that respect I can tell you that you are headed in the right direction for your goal.
In case you have not already considered the issue (though likely you have), you might make sure you have clearly delineated your requirements for a perfect slavonic text. That is, the documents we have show some degree of variability (which you of course have noted, hence your goal); much of this derives from the regional differences in the native speech of the scribes themselves. If we choose a particular word and search for its "correct" slavonic form, my personal method would be to say its form "should" be what results from taking the related word in Proto-Indo-European and applying the generally accepted rules of derivation for the south slavic family (specifically OCS).
The issue is this: if the word in question has no antecedent in Proto-Indo-European, what do we do? Perhaps we should pick one dialectal form as "correct"... but then which dialect? Which dialect was more "properly slavonic" at that time?
You will of course have to wrestle with these issues and come to a conclusion appropriate to your goals. In a pragmatic sense, you could use Miklosich's Lexicon Palaeoslovenico-Graeco-Latinum (see the OCS Online lessons for a full bibliography)... his dictionary is appropriate for a wider range of early slavonic languages. But if memory serves me, I vaguely recall that Lunt's dictionary of OCS differed in certain words as regards the yus/yat' distinctions. But greater scholars than Lunt on OCS are difficult to find... so in those situations it might be difficult to decide which form is more correct.
I understand that the upshot of the above is a non-answer, but hopefully it may help point you in the direction of more complete answers. Best of luck with your endeavor, and please do not hesitate to ask if other questions should arise.