Building a Low Mileage Motor - Does This Allow any Shortcuts?
 

First of all I have a 94, stock block GT28RS @ 15psi. Want more power, dont want to blow it up.

Let's say I had a 2001 engine with less than 15k miles on it, and I wanted to build it for ~350-375 whp. Are there any advantages to paying more money to get a low mileage engine? Can any machining be skipped? No need to do any work on the valvetrain?

I am just starting to think about a built engine so I can up the boost, maybe run a GTX2863 in the future, but I would also like to have a VVT head and the option to bolt on a EUDM squaretop manifold which is why I was looking at an 01 engine. Along with this would probably be a MS2PNP and VVTuner.

Virtually no benefit to having a low-miles core.

Even if its a long block?

You could probably just do rods and an oil pump ;) You can't replace the pistons without a rehone because the rings won't seat. If you machine the block you need to have it cleaned, if you need to have it cleaned you might as well do the whole rebuild process because your going to do a complete disassembly anyways.

I'd definitely spend a lil more on a low mileage head if you don't plan to do any headwork.
As for the block, like they said, doens't matter.
Also I'd NEVER build a motor without at least removing/inspecting the pistons/skirts and ALWAYS replacing the rings (and mild hone). That's just common sense.

Would I need to get the head resurfaced if I don't do any work to it, or is that asking for a blown head gasket?

You need to atleast have the head checked for flatness. Any machine shop can do this and probably shouldn't charge you anything.