130 spec 1800 silvertop will outrun a 2.0. there arent plenty of 2.0 silvertops around, there wasnt plenty, when they were new.
my advice would be to get a 1.8 silvertop from an escort, either in 130 spec, or up to 130 spec......or get an 1.8 silvertop from an escort and fit carbs for easy peasy power
1.8 130 spec silvertop has less power and torque than a 2.0 silvertop, wont ourtrun it!! trust me I know A LOT ABOUT ZETECS!! the 2.0 has more potential too. When you replaced your 1.6 with a 1.8 130 spec I could not understand that... you should of dropped the 2.0 in there instead, however depends on how how far you want to mod the engine.
There are tons of 2.0 Silvertops around mate, always have been, they are anything but rare or hard to find. Ebay will show up some alone.
personally i'd go blacktop zetec, if you got the money, spanking new crate engine, £835.