well i am no expert but I am looking into doing a 393 also. From the most part its a 3.85 stroke crank with 351w rods and 302 pistons so would still be using a 351w head.
Now I have seen were people are using other length rods don't know what the advantage/disadvantage would be.
I personally would be interested in knowing what kind of work should be done at the machine shop as far as getting the block ready. What has to be done, what should be done and what can be skipped.
83 351w block .30 over
MSD 6AL, MSD Distributer #8584, Edelbrock PERFORMER RPM 2.02" INTAKE VALVES #60259, Comp cam #35-246-3 519 lift intake, 523 lift exhaust, 28in M/T slicks, Holly 750DP, Subframe connectors, Calvert complete rear pieces, 4.33 9in, hooker header, c4