Fuel cams on Lucas race metering come in a variety of different shapes and sizes. Each one unique to a particular engine and horsepower range. How do you compare different cams, or design a new cam? We use a simple degree wheel and a pair of calipers to measure and document cams. Place the cam in the center of the degree wheel with the throttle linkage hole centered on the "0" line and carefully measure with calipers along various degree lines. If your cam is used, it is sometimes easy to see a telltale mark showing the range of use. Document the dimensions, trace the cam for quick visual reference, and write down all important data associated with this cam like shims, motor, car etc.
The Lucas manual "Notes on Installation and Calibration - Racing Cars" has instructions on cam control curve design. 

These three fuel cams, Small block Chevy Can-Am, Big block
Chevy offshore boat, and  a 4 cylinder SV, illustrate the range of differences. (click to enlarge)