first of all, good luck with your surgery, but I am afraid these PVA matrices simply won't work. The reason is simple: they don't have the amino groups present in the gelatin. The dyes (in their ionic form) are attracted to the protonated amino groups (gelatin), so that's why they are held in place even when you rinse the matrix in acetic acid solution. When you make the contact with the receiving paper, there is a gradient in pH between the matrix and the receiving gelatin, so the dye molecules are driven there. Simply put, the dye molecules are more attracted to a gelatin environment with pH 6 rather than about pH 4 (just to make a long story short).
just my 2 cents