383 with Eddy heads!

PeeTreed, I made a mistake when I clicked on the Lunati web site. I clicked the 04 cam, not the 03 cam. The one you list would work. Though the duration is short, you would just have to time it well. The distributor would need to be dialled in right and the carb would need some good attention. The combo of these two parts, the carb and distributor need to work together well on a small cam in a high compression engine. Or a cam on the smallish side and a 10-1+ engine. Iron or aluminium head. The aluminium helps the issue.

The math works like this;

Intake;
.494 /1.5 = .32933333333-------
.3293 X 1.6 = .5269 (Round off to .527)

Exhaust works out to be .547

On cam size, considering that the 383 is moving a lot of weight, your duration can not be to large. If you start to move up in duration, then you will need more stall and possibly gear. Though 4.10's are a good gear for a weighty truck.

More duration equals higher RPM band. Can you afford this?
The more lift you have has a direct impact on HP. The better the head flows, the more HP you can add. (Though I have noted it isn't much unless your engine is a race set up. Even then, it is only a few ponies over a lower lift cam.)

IMO, it is better to get the duration right over the useable lift a cam is ground with.

IF you think you can get a way with more duration, the next step up is as far as I myself would go in the Voodoo (60304) or Comp Cam (275HL)
http://www.lunatipower.com/Product.aspx?id=1580&gid=287
(.547/.568 lift w/a 1.6 rocker)
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=711&sb=2
(.560 lift w/a 1.6 rocker)

For myself, this is more in line spec. wise with what I would like to use with an Edelbrock head in the truck. (or car.)

More cam than this would be a problem with the build parts listed. I think the converter would be the first issue next to the trucks weight.