redline?

[292farmer]

i put my tach on today in my 1972 gmc c20 a sunpro 2 5/8" not too big but doesn't distract from the clean stock interior, and i wasnt sure what the redline was i thought maybe 5000? but i was revving it and finally seeing the rpms corresponding with sound and around 3500rpms it sounded like it was gonna shoot a piston to the moon my dad says he remembers his 292 he threw in a jeep had a factory suggested 4200rpm redline is this correct? i didnt see any redline suggestions in my manuals thanks guys