To design a fort unit into the A&A system.
Inf cost 3 IPC, and def on 2 and att on 1, for a total of 3 combat values, so lets say 1 IPC equals 1 combat value.
Tanks cost 6 IPC and have a total combat value of 6. The benefit of movement seem to be an extra reward for buing this expansive unit.
Artillery cost 4 IPC and have a total combat value of 4, plus it boost up one matching infantry, making a total combat value of 5.
Blockhouse could cost 5 IPC. The fortification units had lesser men than infantry units or armour units, but heavier guns, so lets pretend it has 1 IPC-worth of infantry, 2 IPC-worth of heavy artillery, 1 IPC-worth of concrete bunker protection and 1 IPC-worth of mine-fields, anti-tank obstacles and barbed wire.
The Blockhouse could roll a die on 4 or less for hit, and take two hits like a battleship.
The Blockhouse could roll 3 dices on 3 or less for hits, and take only one hit, just to simplyfie the system, but this would also depart from the classic system.
The Blockhouse could half the attacking value, so 4 attacking infantry can only roll like 2 dices, or a tank hit on 1 only.