Found this with a quick web search-
http://www.ericgreeneassociates.com/images/Boat_Longevity.pdf
Like some other high-quality boats, Ericson Yachts used quality layup procedures and good engineering. I would no qualms about a "50 year old E-27".
There are guys around the nation rebuilding frp boats dating from the 60's, and once refitted they are better than new.
(Of course, given the low quality of many of the new production boats these days, that is depressingly easy to believe.
)
Even boats built thinly are lasting well, and I know a guy locally who has rebuilt several Venture 21's into fast day sailer/racers, and is using the basic hull with no added layup. He does put better rigging on them than the original undersized wiring, tho.
Looking around our 150 boat moorage, the only "deterioration" I see on boats dating back to the 70's and earlier is the outer layer of gel coat. The UV slowly thins it out to where owners have to paint their decks & cabins.
Get a good survey and move forward, or not, but not due to any fears about the basic construction somehow going away.
I also know a couple that has repainted their 60's Cal 40 and raced it a lot -- to Hawaii and back several times. No structural problems at all.
Good pedigree is important, and an Ericson gives you that.