I seem to remember L&C Stymie Lightline from the early to mid 70s. I'm pretty
sure that Mecanorma had it in their range of transfer lettering called
Normatype. Perhaps you could look first in whatever library has digitized
versions of those designs. Or you could try to track down Tom Carnese (is
that correct spelling?) in NYC or wherever he now lives, since he's one of
the original creators.