Modifying my stovetop fittings need SS advice

[CaptainJackson]

brass and SS with silicon.jpg

The first still I got was the stovetop stainless/copper variety. It works ok but the fittings use a silicon gasket between the brass fittings and the stainless flexible pipe and aside from the fact that I dont want silicon touching my product, the gaskets fall apart.
I have tried to just convert this all to flared copper but the fittings I need just dont seem to be available.
I bought some 3/8" SS washers and stacked them inside the brass fitting so the SS pipe would fit snugly and I am planning on just using APF paste like lots of people.
My question is this: I plan to visit my local machine shop and get these SS spacers made. Is there any type of SS that should or should not be considered?
I'm pretty handy but am not familiar enough with the types of SS and which would be the best to use or avoid.
Any other advice also welcome!

Thanks,
CJ