I don’t think triple calendar was a thing on Speedmasters until at least the 1990s. Even the first day+date in a proper Speedmaster was [googles] er, 1987, it sez here.
Ah i see....shows what i know.!
I am doing some more research before i jump in. I will be looking for a Professional 145.022 then. 1978 model year seems to be quit hard to locate, i found a 1979 on Chrono24 for 5k.
Really after a triple date but would consider any Speedmaster, 1978 vintage only though.
Let me know if anything pops up.
Ta