Even being Airborne troops doesn't qualify them for "superfirepower" squads.
The most common weapon of infantry paratrops and glidermen was the M1 garand. In Normandy only the para squad had BAR's (one) and theorically no SMG at all. Gliderborne infantry squads did not have BAR's nor SMG's. It wasn't until December in the Ardennes than gliderborne infantry was authorized a BAR for each squad. So gliderborne infantry us squads should be somethig in between 457 or 557 until december 1944 to reflect their reduced firepower vs para squads.
While they didn't get BARs until lateish in '44, the para squad had 2 x M1919A6 LMG. By the end of '44 one of the M1919A6 was replaced by a BAR. Now while I agree that a BAR is not the equal of a M1919A6, ASL treats all inherent LMG roughly the same, whether they are Bren/ZB-26/30, Madsens, DP-28, MG-34/42 or BAR, the MG-34/42 giving the German rifle squad spraying fire and a hex extra range. That is the existing pattern, like it or not. All elite bolt action rifle squads are 4-R-M, as are many 1st line squads.
The US 748 descended from the SL era 847, which, like the German 838, was an impressionistic bogeyman. I would have seen a 667 as being closer, possibly allow a 767 to give an extra CC advantage.