and go to the library section. Their Orange Handbook contains a section at the back with a cross reference from all the old EN numbers to their modern equivalents.
They say that EN3 is equivalent to 055M15, and that 070M20 is nearer to EN3A.
This is probably splitting hairs, but I do not agree that 055M15 is equivalent to the old EN3 grade. The new 070M20 is obviously identical to EN3A, but I still think this is a better equivalent based on the C & Mn content:
EN3 0.25 max C 1.0 max Mn
EN3A 0.16-0.24 C 0.50-0.90 Mn
070M20 0.16-0.24 C 0.50-0.90 Mn
055M15 0.20 max C 0.80 max Mn
Anyway, it sounds like you found what you needed. Good luck.