I did - thank you everyone for all the input.

It has always been my experience that you will not make as much power with an average port as a good port by throwing duration at the poor one. Each cylinder head by design will have flow limitations and sooner or later the port itself must be addressed to make power rather than trying to crutch it with duration. An inefficient port will only flow a limited amount of working fluid per given period of time the simple way to flow more fluid is to increase the period of time (duration), correct? To a point, until the cure eventually becomes worse than the cause. In a N/A BBC, cam duration in excess of 236* will produce negligible increases in peak torque, instead increasing the rpm at which peak torque is made, eventually moving peak TQ/HP out of any useable range of non-competition boaters. Some side effects of increased duration are increase in overlap and the possibility of reversion in wet exhaust, poor BSFC numbers, and reduced idle quality. If you cam outside your useable RPM range the result is torque loading your drive, a subject Julie addresses very well.

The more efficient the cylinder head the less duration is necessary to make peak power and the easier to place that power in a range that will be useful in your application. The best cylinder head is the one that meets the flow requirements (peak rpm/displacement) of your engine with the proper cross sectional area and the smallest port volume. An example of two head options on a 502 is a stock GM 990 (320cc) and an AFR 305 CNC chamber only. Flow is at 28” water and the 990 numbers are “good port” intake figures.
The 990 head flows an average between .200”- .700”
243.9/197.4…..I/E Ratio…..67%…..
vs.
297.2/235.7…..I/E Ratio…..79% for the 305 AFR
The AFR flows .97 CFM per CC intake vs. .76 CFM per CC for GM.
The AFR does this with 15 Cc less port volume. The figures illustrate the significant power potential differential between the two heads and the completely different cam profiles necessary to optimize them. As Raylar stated AFR/Profiler is the class of the field with many good options in between. Examine the average of low/mid/high lift numbers within you lift range. Peak flow in the .700”+ range are meaningless if you aren’t camming for them. Select camshaft duration by engine mechanical parameters, flow and target TQ/HP peaks for a broad power band trying to maintain 90% of peak TQ from approx 3000 rpm up. Look for a lobe family with the optimum reliable lobe area and lift requirements.
Bob