the V8 Chev started in 55, and were an option from then on - as I said, very easy install, and the best exhaust to use is the original "rams horn" manifolds - aside from the perfect fit, they work well 'exhausting', and I'd consider proposed use and finances before getting into 'building' a 327 for feel good power - the stock 327 is strong enuff to spin your tires in that 3200# truck, prolly in 2nd gear
I believe the only kinda cranks they put in any truck were the forged ones - at any rate cast cranks were not common til after 67, and unless you're planning on race track revs, either crank is fine, and reports are cast ones actually break less - why they switched to them later I think - not sure about the pistons being forged, but whichever couldn't possibly be a problem for an 'ordinary' driver
sodium filled valves are for heat dissapation, but I'd be suprised if GM put that extra cost into a truck motor, more likely they'd be in the vette 327, if at all - if the valves are still good, you'd re-use them, but more important is putting in hardened seats if you redo the heads, and checking the valve springs
for a cam, it depends on what you're doing w/ it - for a driver, can you afford the price at the pump if you're jumping on something that's got a hi-perf cam in it just for the feel of it? do you expect to be pullin much weight regular? get an RV cam - ask the machine shop based on your use, what they'd recommend - if you're rebuilding it, count on replaceing the cam at any rate, cuz the small block cams wear fast
