yours looks similar to mine but a bit newer, in the second picture if you look to the right of the fan there is an outline of the tag, thats your serial number.
From what i've read in researching mine Whispers came out in 73, and have different serial number then previous generation. my serial is c1560r4s, so if your tag is similar then its pre whisper. not much info on them but main thing on blade maintenance hasn't really changed much, i've been using whisper manual to set my resharpenned blades. Engines in these are mostly ford inline 4 cyl, that been used in pretty much anything and everything up into the late 80's maybe 90's. pretty simple to find info on those.
to get paint off the tag i used propane torch, this way you dont scratch stamped letters. or paint stripper. I wouldn't grind on that
