One step forward, but 15 years back 
Help from Alberto, selling vintage Lancia parts on Ebay and whose father keeps a vintage car museum in Italy--who provided the next clue--that the 'big' pins similar to the Goose latches are from a Lancia Ardea! The postwar Ardea had the same opposing doors as the later Appia, but the Appia pins were downsized (as I can tell) to ~14mm diameter on an M8 thread, vs. 17mm diameter on M10 thread. But finally, if the latching pin (in the latch) is the same, Appia pins might just work.
Somewhere between the Appia (which stopped production in 1963) and the similar latch used on Grecav Eke, there is an answer waiting for us on our ~1967 DeTomaso... the contermporary Perno guida por chiusura sportelloni may still be found...But if I can size up the rubber bumper, I have enough to hold my engine covers down...! Lee
