I've seen OHV conversions before but I've never seen as much "verbage" on a rocker cover before. Was this common?
VERY early version of the Miller Schofield/Cragar head, I think this is the reproduction head & cover. I had an original and MILLER was ground off, there may be as many as 3 other type covers. I'm sure someone will post photos.
My Morton & Brett says Morton and Brett Indianapolis, Indiana. Not quite the amount on yours but a lot compared to after market valve covers today.
you should realise that these heads were designed when the car was still a new(ish) device and knowledge about running cars was not that easy to come by. Most engines,especially truck units carried details cast into them about tappet clearance,recommended oils etc . Today most folks wouldn't know what was under the hood,let alone worry about the type of oil in their car so you get a little fed mandated sticker stuck under the hood someplace with tune up specs. Even that is redundant on cars built after 2004 .
Most just had their name cast in the cover, the exception is the Miller/Cragar pictured above. There must have been 50 OHV heads made for the A/B Ford.