im guessing this is a sierra engine yeah! i dont know any of the 'codes'.

basiclly, if it is, it all boils down to your budget.

if your on a tight budget, replace the head with a 1.6 hemi cvh head, drop in some 1.8 zetec pistons along with a bore home/bore, new rings and bearings etc etc. these days twin carbs are cheap enough, and you should be able to find a setup 2nd hand for £300 ish. drop them on and get them tuned and your away.