Welcome back!
The serial number is no help, your best bet is to find a production date or inspection sticker somewhere on the amp chassis. I don't think Fender ever offered the Coliseum, but I'm not the most up to date on the Fender era stuff.
Sunn 2 X 15 cabs seem to love JBL's particularly the AlNiCo D and K series. I can't tell for sure from the pics if it's a center ported 200S cab, but if so they really shine with a set of old JBL's in them.
AFAIK that old sparkly cloth is long gone. You can get the later Sunn style rectangular pattern cloth, both "brand new" looking as well as aged looking types.
Do a grill cloth search and you'll get a wealth of info about where and how to get it.