And that last point, it seems to me, supports the idea of a "yee" pronunciation - since Burke nowhere else uses an "altered spelling", why would he here? "Ye" for "yee" is not an altered spelling; "ye" for "yih", etc., would be ...

I haven't been able to find much else on-line, other than several mediocre performances on youtube - in which the singers do say "yee", but as you pointed out earlier, that doesn't necessarily mean anything. Tried to e-mail Jim Payne, but the mail bounced back ...