The other point that I think is critically important is the additional thickness and higher torque than the 5.0 that the 351W has. Think about it, you have 1/2" head bolts, thicker webbing, MUCH larger bearing journals, and the list goes on. These motors are perfect for blower/nitrous setups that wanna live for more than a year. Yeah, I know, you CAN make a 5.0 live under boost and whatnot, but for the extra strain and blown head gaskets, IMHO it's worth it. This is the way I'm going, with O-ringed Trick Flow heads, forged crank, Novi 2000, etc. This is kinda the way Dan's Death Machine is set up, and it's lived for quite a while with the clutch being the only problem. I say build it once and never again. Okay, rant's over.
1SILLYGT, check out the Articles link over there on the left, you'll find a section on all that you need to swap in a 351W. Again, cost is a big thing when doing this, but is worth it in the long run. Be sure your tranny can take it, though!!!