I have first gen Athena / Chorus / CDA running until around '92 when the fixing bolts changed in the '92 catalogue.
I've bought 2 or 3 1st and 3nd gen recently the cheapest of which was around £20 for a NOS 2nd gen. With a following wind £30 - £40 should be possible. Strippped cleaned and rebuilt it would look great.
Paul
Devizes. Wiltshire