Pressure spec on the Vortec BIG block is 58-62 psi; this is slightly less than the small block - it doesn't take that extra bump of pressure to run the actual individual injectors on the big block vs. the central injector/poppet valve arrangement on small block which has a spec of 60-66.
Hook gauge to test port and have a helper turn your key on but do not start the engine. You're watching for initial pressure reading then also what it does when the system loses prime. If it falls off immediately that's suspect. (Most TBI's will fall off immediately but I expect the Vortec holds prime for a while, IF I recall correctly).
Crank it up and watch the pressure at idle, then again as you bump the throttle. Should stay within the spec and possibly spike a tiny bit on the bump.
At your mileage I wouldn't expect pressure issues but it's always good to know. Could have got some bad fuel and clogged the filter, even damaged the pump, particularly if the truck sat for several months+ with fuel in it, modern fuel goes bad quickly and is becomes very corrosive from water absorption due to the ethanol content.
Let it sit a while before removing the test gauge. Wad up a paper towel around the area so that you don't end up with a little puddle of fuel under the plenum, because it will spray a small amount when you take the hose off. (that's of course assuming your gauge doesn't have a pressure release on it)
Richard