My criterium I bought in 1980 was too and it rode lovely. Back last summer I happened to have some frames and a pair of scales to hand, so what else could I do?
Raleigh Sirocco (23.5") frame, forks and headset came to 3.2kg
Raleigh Elan (21.5") frame, forks, heeadset and BB was 3.7kg
Carlton 70s truwel (21.5") frame forks and hs was incredibly only 3.5kg so a lighter bottom bracket could eliminate that extra weight!
Edit: the Raleigh frames are 501