I'd go with stainless. Zinc plated bolts have an irregular surface and are bound to rust in time with all damage due to wrenches and screwdrivers. Moreover the looks of stainless is much better (that counts too don't you think).
Here in the Netherlands any hardware store can supply stainless steel bolts and screws so it shouldn't be too hard.
You don't stop playing because you get older,
you get older because you stop playing.