Help: The right Fly Line for an old rod?

I've inherited an old 12 foot rod of British origin. Glass rod and about medium to heavy weight. Seems to be a spy rod. Thing is - it's got no marking on it for the line - so anyone know how I can figure out what's best? I figure with a 12 ft. spey it should be between 8 and 12 - but I am not sure. Any help is really cool. Thank alot. :rolleyes:

Big K1

Large Member
Visit Aaron's(Riverrun Anglers) Saturday get together at the mouth of the Tolt on the Snoqualmie River. There will be plenty of lines for you to try.