IIRC PYRO said it would have .50's in the turrets to give it better defensive firepower.
So, I guess it will be a late model MkIII.
The MkIII had Packard Merlin engines of 1640hp, which by 1943 featured paddle-blade props that improved takeoff and climb performance.
In 1944 the new, roomier "Rose" rear turret with two .50 calibre guns was introduced.
50 late production MkIII's were also fitted with a Martin dorsal turret with two .50's.
The Lancaster should be quite effective in AH I think, especially if it has options for the 4,000lb, 8,000lb or 12,000lb "Cookie" bombs, and also the 12,000lb "Tallboy" deep-penetration bomb.
Of course with the Tallboy, it wouldn't be too much trouble for a single Lancaster to take out the HQ...