Nitriding and crank grinding

Quick question or two here. When grinding a cast crank (say for example a 360 crank to 340 mains) and removing lots of material, can it be nitrided?
Or is that just for forged cranks?
Is it necessary if possible?
He doesn't feel grinding a 360 crank down this far will affect strength, but it will remove all surface hardening?

What are your feelings on cutting down a 360 crank to fit 340 mains? I realise the scat cast crank is $289 bucks,but I might have scored a FREE 360 crank. So I could potentially have a 3.58 340 main crank for the cost of grinding it. Acourse balancing costs might make a stock crank a bad idea.

Local machinist wants $150 for grinding a crank,no matter what crank or how much material removed. That's canuck bucks in a remote area.

Also wants $25 per hole for boring/honing. So $200 will get you a hot tank,cam bearings and bore/hone. $150 to deck a block. Not bad prices for here. He's the only guy available locally. More of a G.M guy...but a good machinist. Dealt with him before.

Im determined to pursue the 349 build for my M. Need torque for that heavy pig. Thanks BJR!