The Vanguard was first 1800cc and then 2-litres.

Different liners and pistons (to get 2088cc) were used in the Ferguson block, which was a deeper casting to enable it to perform chassis duties. The camshaft would have been different, the distributor would have had a different advance curve, it certainly had a different rotor button (with rev limiter). The head was probably the same, the flywheel would have differed.

I recall people telling me they'd used Ferguson liners and pistons to increase the capacity of their Vanguards. Later the TRs used bigger liners and pistons too.