Forgive me butting in Chris but you seem to be turning a blind eye to Magnet's strong hints about the state of your engine, so let me be more forthright.
Running the engine for a year without adequate lubrication has spoiled the piston ring sealing in the cylinders as your compression figures clearly demonstrate. (Incidently that's likely to mean the big end and main bearings are also clapped out.) No amount of new oil pumps are going to restore the rings and bores, so there will be exhaust blow past leading to smoke, high emissions, blocked exhaust and MOT failure.
I fear you have left it to late to save that engine.