crankshaft recommendations

The eagle cast sucks. The forged are much better. Not as good as K1, but decent. MP is still Scat and they can make 600hp at the crank in a properly built package. I have two that exceed that with nitrous and have for 8 years now.
But that being said - you don't need a 4" stroke and it gets pricey. Just use what you have but in terms of the crank going to .030 - it should be nitrided because you're cutting away all the hardening. 340 forged cranks are not hard to find (nor are 273 or 318 forged) so I'd replace it.