The crank was marked as English threaded or the auction was marked as such?

I ran into the same issue recently. I was going to tap my 93 but had the same reservations. I began looking for pedals and found a couple pairs of Lyotard rat traps. I really like them with clips and straps. Now I have two French threaded 93s and no real desire to tap them to 9/16" x 20.

The Stronglight 93 was not a rare crankset by any means so far as I know. If you're a dedicated SPD guy then I don't see an issue having them tapped or you could just continue to look for one that already has English threads.