The original MRB I built was an early 80's organisation focused on BMP 1 and reflecting the Force structures of the late 70's. As the Soviets moved firmly into the non Nuclear doctrine they undertook a number of significant organisational reforms. In the MRB this created Air Defence and AGS platoons in all battalions, AT Platoons in BTR Battalions and manoeuvre support and AT detachments within companies. The AT detachments did not appear in BMP based units. The Mortar platoon became a battery and could be either 120mm or Vaselik. The net result of this was more vehicles and weapon systems but with a firm emphasis of increasing fire support both direct and indirect.
The upgrade of vehicles was seldom consistent and within the BMP fleet you could see that active management of this might optimise your fire support options. A mix of BMP 1P and BMP2 for a late 80s MRB would seem appropriate. I have used the BMP 1Ps in the support platoons and the BMP2s for the rifle companies
The BMP 1 Ps are ACE wagons with the Sagger and launch rail removed and one of Elhiems AT 4 systems mounted to the right of the gunners hatch, you could also add three smoke grenade dischargers to the either side of the turret simmilar to the mounting on the BMP2. BMP1P commenced fielding from 1980 and BMP2 from 1981.
I have created 3 SA7 teams each of two figures for the air defence platoon which fielded 9 SA7 and 2 AGS 17 representing the 6 systems deployed in the direct fire support platoon. The Morter battery is mounted in MTLB and deploys 2 120mm Morter. The rifle companies all have an additional figure with a PKM GPMG, I am currently trying to resolve if these were PKM or PKMS with tripod.
The later Battalion deployed more BMPs and consolidated the fire support elements into definitive groups, my current early 80s force, has an AGS 17 in the Battalion HQ which I am now considering dropping. This is the organisation around which many of the forward detachments are built as the BMP Regiment was more likely to be in the second echelon than the first.
ORBAT - 1980's Soviet MRR and TRR, Part 1 Deployment and ORBAT
TTP - Soviet Forward Detachment as a Covering Force
Wargames Unite - Soviet Early 80's MRB