For the Battalion-level, I propose something more or less along the following lines:

A Weapons Company consisting of a Heavy Machine Gun Platoon, with 8 or 9 40 mm GMGs; a Mortar Platoon with 8-9 81 mm Medium (Foot Infantry) or 120 mm Heavy Mortars (Armoured Infantry); an Anti-Tank Platoon with 16-18 Medium (Foot Infantry) or Heavy (Armoured Infantry) ATGM Launchers; a Pioneer Platoon of 3-4 Sections for Field Engineer Battlefield Tasks; and a Reconnaissance Platoon with 6-8 Recce Teams, and 3-4 Sniper Teams.

Also, in Armoured/Mechanized Infantry Battalions, a Carrier Company of 4 or 5 Carrier Platoons (4-5 APC/MICV/IFV each). This would centralise training and maintenance; each Carrier Platoon may be attached to a given Company on a habitual basis to encourage familiarity and tactical cooperation.

I am concerned however, that wherever possible, even Battalion-level Heavy Weapons should be capable of being man-packed (including in Armoured/Mechanized Infantry Battalions). As such, I view the 120 mm Mortar and the TOW (and like Heavy ATGMs) as something that I would prefer to see organized in their own Companies, and located at Regiment/Brigade level; not to mention that I suspect that they are more effectively used that way most of the time anyway. I would much prefer not to have 120 mm Mortars and TOW-type ATGMs organic to the Infantry Battalion, but rather attached to them from Regimental/Brigade-level.