Choosing the right stroke for a 340

Absolutely! But my thoughts are if you're going with a 3.58 stroke, then just start with a 360 and save yourself the cost of a stroker crank for the 340. In that case, a set of pistons and you're there. Even if you want a bigger bore than you feel comfortable with in the 360, sleeve it and go big (under $80 a hole locally).
Hmm... now I'm thinking of a 273 block sleeved to a 340 bore with a 360 crank with the mains turned down... and being able to just keep pointing out the "273" cast into the side of the block to all the 5.0 blue oval boys...
i've known of 'class' circuit race guys that cheat by cutting the 273 casting numbers out of the side of the block and welding them into the side of 340 or 360 blocks.