If you mean the 1974 Jerusalem 73 MS international Philatelic Exhibition mini sheet set of 3 issued 25 03 74 as a set of 3 sheets with Bale number MS11 MS12 MS13 then these do have a gum variety listed in Bale. Bale who also gives the Scott number as 532-534.
Bale describes this as 1st paper shiny gum thin paper, 2nd printing thick paper matte gum.
Bale catalogues the first printing as $.60 set and second printing as $3 set.
There are much rarer varieties of this issue in Bale eg imperforate listed at $700 each sheet and gutter pair sheets that is 2 sheets joined together at $800 .
Please clarify if this is the set you mean in your post.
I'll just add that the sheets or stamp cut-outs with Matt Gum (and slightly thicker paper) were from a special printing of the sheet that was only sold at the Exhibition by the organizers. Many were used on Covers with pictorial Exhibition postmarks.
...Interesting. I recently purchased 2 sets,(MNH) one has a gloss gum, the other dull. As yet, I haven't found any reference to them.
