How to date Alan frames?

NEVER respray an ALAN
If it is correct, the aluminium is anodised, not painted.
Painting (and re-paining) is never necessary, thus unforgiveable.
The only thing you may consider is replacing damaged or non-original decals.

Record means that you have a Super Record type frame, not the earlier / cheaper/ lower-end Competition type.
The easiest way to find that out is:

• Super Record frames have the seat stays screwed and glued into the seat lug, more or less as an integration (see picture in LPG's postings above).
  
• Competition frames have the seat stays bolted to the seat lug (see picture in Unicanitor's postings above).