The 80's monte carlo 305's were as follows (yours should be real close)
LG4(LS) tach(if present) yellow line at 4500 rpm red line 5000 rpm
L69 H.O.(SS, SC) yellow line at 5000 rpm red line at 5500 rpm
I think my car made it up to 4000 rpm maybe twice in the last 5 years, however all this...