The Shimano derailleur is a RD 7402 which was produced from 1989 - 1996.
http://velobase.com/ViewComponent.as...8c20d&Enum=108
RD-7402 (8spd)
HB-7402 8spd cassette hub (130mm) Hyperglide

The front derailleur is as you suggested not Shimano, and is a Campagnolo, no model number or year visible.

The crankset is a Shimano 600 (FC 6207) with date stamp "JH". From the Vintage Trek website this is apparently August 1985.

The brakes are Shimano model BR-6208 with date stamp "JJ" denoting Oct 1985.

I am pretty sure the bike was purchased before the 90's, so with the derailleur being the newest I would say the year is 1989, making it 23 years old, pretty much what I suspected.