How much nitrous can I safely run?

[BrentRS1985]

I have a 4 bolt main 350, stainless steel crank (I can't find any info on stainless cranks, but thats what the machine shop told me I had), 302 chevy (pink) rods and speed pro forged aluminum pistons. How much do you think my bottom end can handle? I don't have arp bolts but will once I put the no2 on it. Good rods aren't too expensive these days so I will probably get new ones just to be safe (any recomendations?). But I really can't afford a $1,000+ crank right now. I am hoping a cast stainless crank is better enough than a plain cast steel crank to handle at least a 150 shot if not a 200. Maybe you guys can tell me what I've got by looking at this picture...

as usual, any help is greatly appreciated!
oh btw, when I get home I think I have a few more pictures of the crank that are high def if they are needed