Has anyone got any idea of what an 85 Merckx would have come with tyre wise?
Probably whatever the original owner fitted as I doubt that a bike of this era would have been bought as a 'complete' bike as bikes are sold now. There were quite a few 700c clinchers around in the mid-80's - including Specialised, Nutrak, Vittoria, Michelin, Clement, Milremo, Wolber and others.
However, doubtful if you'll find an original tyre from this date that would be safe to use. The Veloflex ones sound a safe bet for a reasonable appearance close to the original.
Today is the yesterday of tomorrow.