S/S is best in my opinion, it gets dirty but really don't need a lot of cleaning whereas alloy even with a coat of lacquer needs care.
Can't help with con rods and such, last place I used went out of business in 1979 (gulp!) Pride and Clarks in East London I seem to remember.
I have an XJ 750 tank in the garage, been there for the last 4 or 5 years, dry stored and stripped, I figure if I haven't used it by now it's never gunna get used, if your interested let me know Jimmy.