Congrats on the GTV!
I can send the 72 GTV & 74 Spider diagrams but I'll need your email address. The 74 & 75 Spider diagrams are quite different so you'll need the 74.
Can't say what the bulb numbers are and they aren't listed in the manual. My first thought would be to pull one from the Spider and see what it is. The numbers should also be somewhere on the BB.
Vintage Motorsport Sept/Oct (with the Maserati 250F on the cover) has a flattering report about the late June '14 vintage event at Thompson Park. Praise for the owner who brought it back. No description of the track, but the photos with plenty of trees and grass looks appealing. FYI.