what max RPM on low comp 273

You didn't mention anything about the exhaust. My "refreshed" 318 2-bbl. with single exhaust (and Lunati Voodoo cam, doesn't do much now) can barely top 100 MPH in a '70 Duster with 2.76 gears. Of course, that's at 7000 ft. above sea level, but I think 118 is pretty good for your car. I think with a cam and a good dual exhaust system you should be able to push 130 MPH with power to spare.