Don Post Kirk masks do not all look alike does anyone notice this? Some look rounder in the face and I’ve seen longer-faced as well…the latter being the Hero.
All mass-produced masks vary slightly but if you are talking about 75 Kirk’s specifically, as it seems you are, the Hero used for H1 was not as long as it seems. Castle definitely added a stretch to the mask but when Warlock wore it in H2 it looked like an entire different mask. Castle had his chin in the neck of the mask many atimes so it shows just how tiny the mask was. Likely 23" or slightly larger. But yeah, the 75 Kirk’s actually varied much less than newer mass-produced masks do. The TOTS H40 literally varied from 23"-24.5"
There was more than one mould used for Kirks too. Different copies of the master mould will introduce their own size/shape variations.
The Kirk masks used in Halloween '78 also appear to be very thin, and of a stretchier latex so they would easily distort to fit their wearer.
My TOTS Kirk is nearly as big as my HII Deluxe, and my Elrod is uncomfortably tiny, yet I’ve read conflicting reports about their size. If there is 1-1.5" variance within batches, that’s quite incredible.