Mondial Qv Exhaust bolts dumb questions

I am in the process of changing my back box to a stainless one I have already tried it and it is great apart from the exhaust olives are knackered,

My questions are:

1, Some of the bolts are a bit manky, can I buy off the shelf stainless ones or do they have to be strengthened/reinforced

2, Secondly are the Qv olives/donuts the same as any other Italian cars i.e. Lancia/fiat as I've been trying to obtain them locally

3, Also the spring exhaust hangers are a bit rusty, does anyone know their proper name/number and how many models are they interchangeable from as i've often seen them on ebay but not for Mondials

Any help would be great