So - the advertised duration obviously begins before .050 valve lift. Advertised lift must be the point where the valve actually begins to lift, to the point where it is completely seated.

The 223 lift @.050 cam could have an advertised lift as high as 280?

I've read Elgin again -

It seems that it all boils down to the relation of duration to TDC/BDC. In other words, on the intake stroke, how soon after BDC the valve closes. And the longer duration favors higher RPM.

Still not sure what my stock 283 would like as a good mid-range cam, once I get done with the suspension.

How would I measure required lift relative to CFM throughput?

Considering the cam as the last choice, I need to see what I dealing with first in rods, pistons and carb, then

I'll be back - Thanks for the info

Bert