From Air Britain’s Liberator book:

Bulloch attacked German warships 13/12/41 flying AM928 OH-L, which was a Mk.I with round nacelles and the short nose, fitted with ASV Mk.II (stickleback aerials) and 20mm cannon. Later he attacked U89 when flying AM917 OH-F, another Mk.I to the same fit. He had flown this on 22/10/41 when carrying out the first squadron attack on a U-boat. On 3.8.42 he sank U597 flying AM929 OH-H, . Another Mk.I, this time without the cannon. With 224 Sq he sank U-514 on 8.7.43 flying Mk.V BZ721 coded R. The Mk.Vs had a longer nose than the Mk.Is and went through a range of modifications states, but probably will have had the chin dome for the later ASV, probably no dorsal turret and possibly BP tail turret.

There may be more, that there’s an awful lot of Liberator histories to plough through, so I think that should be enough to be going on with.