^Agree, you won't get near 200hp with CIS pistons and cams.
Cheapest route is a set of JE 9.5:1 pistons, if you have nikasil jugs you might get lucky and be in spec, if not or alusil jugs your price of the P&C set just doubled. Plus a set of cams, headwork, carb jeting, etc.
But if you did all this the carbs should have bigger venturi's and there's not many parts available for Zeniths.
Performance costs can add up fast, known as the 'The slippery slope'.
Big thing is it's a lot of research, work and you have to do things right the first time.
The absolute cheapest route is mild cams better suited to the carbs and too be happy with 160-ish HP.
