If you are looking for a fork for "your Hampsten" then ... you are in luck: there is no way to find out what tubes it was made of (for pro frames a fork made of other tubes - more durable - was often added)
What remains to be established is what kind of fork crown was used at the time - you could choose between the classic "slope" or the no less classic "flat"; the "slope" did not change, the "flat" did - you would need one with the EM logo with small reinforcements... but you have a photo and with a bit of luck you will see the fork crown there....
And now the most important - forkouts !
....a actually the inscription on the forkouts - if on the dropouts you have BREV. CAMPAGNOLO then on a matched fork you should have the same...
( if you have EDDY MERCKX then analogically)
Good luck!