They also came in 144 BCD with no provision for a granny ring, if you want a "pure road race" crank.
Both were designed by Jim Merz, once of the first things he did when he went to work for the Specials.
The 110/74 crank was vastly more popular of course; you hardly ever see the 144 version.
Specialized and others made many sizes of rings in 110, including 52t. Not the most common, but I wouldn't call them rare. The bigger rings were popular on tandems.
I probably have one or more 52s, probably even a 54, hit me up in PM if you want me to go look. I won't charge premuim prices for those sizes because I'll never use rings that big myself.
My pile of 110 rings isn't super convenient, so I'd rather not go inventory them right now unless you're actually interested.
Watch out for cracks in the right crank, right where the two adjacent spider arms join the crank. I have two 110/74 Flag cranks, both cracked there. I recently considered buying another set I saw on ebay, until I looked real close at the photos, and yep sure enough, same crack in the same place. I alerted the seller, and he didn't take it down — either he doesn't see the crack and/or doesn't believe me, or he's just hoping the guy who buys it doesn't get hurt too bad when the crank breaks!
To be honest, I've never seen one completely break. I didn't keep riding the ones where I found cracks, so I don't know what happens if you keep riding them. Some fatigue cracks don't propagate, or do so only very slowly. Lots of folks got good long miles on their flag cranks without them ever cracking, so it is by no means inevitable. I am large, and both my cracked cranks are 180 mm length = more leverage amplifying my already "ample" weightiness.
Oh yeah right, just remembered, one of my flag cranks was mostly ridden by my friend Fred who is about 6'7" and was a semi-serious racer. The Flags were on his touring bike, but that guy always pedaled hard. I got the crank from him with the crack in it already. I filed out the cracked metal with a needle file and polished out the file marks. Still have that crank around here somewhere, might put it back on a bike one of these days. That repair can suffice, if you catch it while the crack is very small. The trick is knowing where the very tip of the crack is, and filing off
all the cracked metal. The tip of the crack can be microscopic, so it's hard to know for sure you got it all. Dye-penetrant testing is recommended.
BTW Campy "old Record" (sometimes called Nuovo Record) cranks were known to crack in that very spot, and the lore I heard reported a few times was that Campy allowed you to file away that sharp edge where they crack, without voiding the warranty. Supposedly the only modification to a Campy part that was allowed. That's just hear-say though, never heard that directly from Campy — grain of salt recommended. But I have filed probably a dozen or two old Record cranks that way over the decades, got fairly good at it. I never had a crack "return" or continue propagating after I had filed one, that I can recall anyway. One some of those cranks, the filing was done prophylactically, before any crack was seen.
But I digress!
Mark B