The plans posted are for the classic Tipo 720 - the first design of the series. On that design, the stab centerline was along the extension of the tuck line toward the rear of the fuselage. This line could be located by laying a straight edge level along the inflexion of the canopy tuck line. In the absence of a mark on a glass fuse, this strikes me generally as the correct location for stabs on all Tipo designs but in the absence of plans or build instructions, it can't be confirmed for a particular version.

I hope that helps,

David.

P.S. A picture of your fuse would help to ascertain what Tipo you have.