The CVH engine doesn't really lend itself to tuning

True you can get it to 120/130 bhp but you will need to spend a lot of money to get it there and keep it there. Certainly you will need to consider manifolding, cams and twin Weber sidedraught carbs and/or Weber DCNF carbs if you can find a set.

One option to consider maybe a Zetec conversion with turnkey 130 bhp engines available for less than a grand !

Arwyn