318 hydraulic lifter preload.

.030-.060" is ideal if you are running to higher revs..... which I'd expect with the new cam. So that is what you should shoot for. If too small, then the valve on that cylinder/valve may not open fully; if too large, then the potential for pump-up and at high revs is increased. Possible variables:

1) The .010" shorter at that valve works out to about .006" at the lifter and pushrod side. So .010' per se is not awful. But, the valve heights as a group may not be all set right.
2) What head gasket do you have? As noted above, the originals were quite a bit thinner than the standard replacement head gaskets like the standard .051" Felpro's. So you likely have lost some preload there, as much as .020"-030". .039" Felpro 1008's would gain back .012" or a bit more over the .051" ones, plus a bit of compression to make it run better. 1008's run around $40 each.
3) Wear on the shafts and rockers. You need to inspect these for wear. Look at that short one and see if the inside of the rocker is worn. It may be a case of replacing only a few rockers.

It kinda sounds like you need to look at the parts you have (like the head gaskets) and then go through the process of assembling the valvetrain and doing some actual checks. With the intake off, you can actually see the preload. With the lifters fully down on a given cylinder (see the link below for procedure), look at the lifter piston and see how far it is below the retainer clip in the top of the lifter. That is the preload. It is quick and easy to check them all, by rotating the crank 90 degrees at a time, starting at TDC for #1 on the power stroke. If they show all very small to no preload by this quick visual check, then it is time to get some checking pushrods and go through the process (as in the same link below).

And, the way to see if the valves are set in the head properly is to measure the valve installed height directly, not by any of the indirect methods mentioned. So if you have serious doubts, take them back to the shop with the spec and ask them to measure them while you watch. If they won't, then throw the heads at them..... just kidding.... BTW, the valve tips being too high is more common than too low.

As for experienced people not knowing.... well if they are GM guys, many of those rockers have adjustable height rocker pivot balls so they never deal with it.

http://www.forabodiesonly.com/mopar/showthread.php?t=345989