Group set avise please, Deore 510 ??

[Subaloo]

Hi,
My LBS has advised a Deore 510 rear mech
I was going to fit a M592 but my LBS suggested this with 48/38/28 chainsets or similar ring set-up.
Plus A Shimano Exage 410 front mech

I'm a bit lost and would be grateful for all advise in how to get a reliable group set for my 89 Montage turn tourer.


Thanks