You may want to check some of the movie supply houses in Hollywood. I sold them several cases of Press 75 bulbs (MAZDAS). These babies would light up a football field from a small aircraft, no kidding. I used them to photograph the WEBN fireworks in Cincinnati years back from the top of a 12 story building and as the fireworks lit the sky, the Press 75 bulbs lit up the Kentucky side of the river banks from across the river, using a clamp light and 9 volt battery to trigger them.
I got $ 32 dollars a piece for these hummers when I sold them to a Hollywood supply company and they paid for the hotel at Yosemite for 5 days. I know where 5 more cases are (12 ea), but my friend will not part with them, yet. When we were young the two of us played with these all the time, his father dealt with military surplus and he had skids of them in the early 1970s.
Good luck on your search, If you do find any Press 75 bulbs, PM me, I'll show you some really cool and stupid fun things to do with them.... I'm still a kid at heart.