Those EPNS are worth little or nothing.
I think, you could bring the true silver ones back to their former glory and polish the lot.
If you had that book with hallmarks, you could better find out yourself. Worth getting it.
In any case, after you have cleaned and polished it, you could visit at least 2 or 3 antique dealers but take your time before making a decision.
Cheers,
Gerry
