You might need to put in a bigger radiator.

Mine has an RS1800 zetec 130ps and it runs quite hot. I'm fitting a new rs1800 fiesta and changing the cooling system to make it identical tom the fiesta one as where the plastic bulkhead has been removed I can fit the fiesta header tank.

An annoying stupid problem is that the bonnet stay doesn't fit anymore so either fit lifters or use a shorter stay such as from a mk1 focus.