I wouldn't vary too much from what you see recommended in cam catalogs, save for maybe a narrower LSA than most cam companies grind them on. If they show 268 duration for xxxx rpm range, in a 383 that is probably about what you need. Bigger motor, more duration. Keep this in mind, that the bigger the motor, the narrower the LSA needs to be when using the same valve sizes. So a 383 motor with 2.14 intake valves might work great at say 110, but a 500 inch stroker might be much happier with a 106 or even less! The narrower LSA provides the overlap to feed all those extra cubes through the same valve overlap/valve size setup.
In a lot of cases, cam companies grind cams with too much LSA, to cover up the problem of guys picking too much cam to start with. But the cost is a motor that performs, OK, but not to its' peak potential for what it is.