Do you mean a manual for the Cosworth, or for a 'normal' Sapphire?

Haynes will do the job for most bits, then the Ford Workshop manuals for the Cossie related parts (which is/was available in printed format) which covers 3dr, Sapphire 2 & 4wd & EsCos LT & ST. There's also a suplemental manual for the RS500.