Having flown the Victor K2, it think reverting it back to a freefall bomber would have been too problematic. There was nothing of the original bombing kit left, except for the NBS navigation system.
Th Black Buck missions required 11 victors on the outbound leg (two as reserve) and five for the return. Of course, some of these aircraft flew twice each mission. The Victor fleet at the time numbered 24, so this was a pretty impressive aircraft generation for such a long range operation.
The value of the Black Buck missions has been questioned frequently - particualrly by a certain vociferous SHAR pilot. A lot of this criticism is based considering the success of the raids in tactical terms. The strategic value of the missions is incalcuable - they sent a clear message to the Argentinians that they were in range. The effect on morale and redistribution of assets is hard to measure.
The Buccaneer was considered for the role and I gather there was a proposed modification to extend it's range. However, the Vulcan was the obvious choice and although the generation of airframes for conventional freefall missions wasn't easy, it was rapidly acheivable. The Nimrod was easily converted to carry freefall bombs - it had been one of it's design parameters. I gather it had dropped PGMs in later times.
And of course, the RN had Polaris. But I expect the use of that systems was considered a little extreme!