There are a number of fitment issues with a 351 instead of a 302. The deck height on a 351W is 9.5" - the 302 is only 8.2". While your heads will bolt on a 351W, because of the extra deck height, the width between them is different requiring a wider lower intake manifold - it's 351 specific. Also because the heads will sit higher and wider on a 351, 351 specific headers will be required. And, you'll need a different hood because with the taller engine there's not enough hood clearance unless you are very selective with your intake, and drop the engine lower in the chassis with different mounts. The common displacements of stroked 351's are 393 and 408.
A properly machined/built stroker will work just fine - the rod/stroke ratio's aren't any worse on a 347 than they are on many big block Chevies. Just be sure you get pistons that don't have the rings intersecting the wrist pin. It may be possible to bore larger than .030" on a 5.0L block, but not without checking the cylinder wall thickness first. THe blocks are known to have some core shift resulting in some finished cyl. walls being thinner than others. The common rule of thumb to be safe is not to go any bigger than 4.030" on the bore. Stock is 4"X3" = 302. 30 over stock is 306 cubes. 327 cubes is 4.000"X3.25". 332 is 4.030" X 3.25". 342 is 4.000"X3.4". 347 is 4.030" X 3.4". Those are the most common combinations for strokers.
Given that this is your first one, and that you want to run boost, I think you'd be better off just buying a 302 short block. And, as long as you've got to do that - get forged dished pistons that will lower your compression ratio so you can run the higher boost levels you'd like to without that thicker head gasket. Please.
