Lister JP straight top liners

[triumphman]

I have been offered  some straight top liners at a reasonable price, I need two of the six for sure but I haven't got round to cleaning the others up yet. The liners in the engine were stepped top and I understand that these were the later ones introduced to overcome a problem with head gasket failure. The lister manual I have says that either can be used as long as they are all the same

So my question is are the straight top liners any good or are they more prone to head gasket problems.