Let me first say I have no personal experience with the Pace Pac 350/300, but the 350/300HP version is, in my opinion, more desirable, and is the engine GMPP should have come out with instead of the 350/290. The 350ci 300HP crate engine uses the same long block used in the "Universal 350" and the 350/290HP engines. The camshaft (.443 intake/.465 exhaust, 214* intake/224* exhaust, 112 LCA) is basically a copy of the cam used in the GMPP 350HO/330HP and 350/350HP circle track crate engines (.435 intake/.460 exhaust, 212* intake/222* exhaust, 112 LCA). It has a few thousandths more lift and 2* more intake/exhaust duration with the same 112* lobe center spacing. The 350/290 uses a 40 year old technology camshaft that was designed for an engine with 11:1 CR. The Pace Pac 350/300 uses a modern split pattern cam designed to be used in lower compression engines, and will have better low end and street manners. The Pace Pac 300 cam will give some of that "rump rump" that we all like, but still have great bottom end. A great feature is Pace prices their 350/300 version for $160 LESS than the 350/290!
From Lunati.com here's the description of the Lunati version of the cam: Advertised Duration (Intake/Exhaust) 280/290 Duration @.050" (Intake/Exhaust) 214/224 Gross Valve Lift (Intake/Exhaust) .443"/.465" Lobe Seperation 112 Intake Center Line 107 RPM Range 1500-5500 Part Number: 10001LK
$99.95 at Summit
To get an idea of what the cam will sound like, here's a video clip of a 350HO start up:
http://www.youtube.com/watch?v=ScHhUQtEiU0
EVERY cam grinder has a cam with those specs, or nearly identical specs, so that should say something about the popularity/usefulness of these cams in the engines lots of guys are running today.
Like oldbogie pointed out, any of these versions can be used for a build up that can make pretty serious power. I would say if you're going to use the engine as is, this would make a great street engine. If you're going to use it for a build up, then just buy the "Universal 350" version for $1500, no use to pay more for parts that you're gonna pull off.
Ed