Hi, It may be that as it is history you require, the Motorsport History section is more suited, but the moderators will sort that out if they deem it necessary
There is a very interesting thread about the Gp5 MK2 Zakspeed cars in the above mentioned section which demonstrates how difficult is it to get info about them. Frank de Jong's website dedicated to Touring Cars gives some info, but reading up on period Appendix J to know what was allowed is a start if you havn't already done so. Zakspeed started with Broadspeed built cars so there is similarity until they took charge and developed them further. There was a blue Mk1 Escort for sale advertised as the Italian Finotto Zakspeed car, but as this was used in competition for many years after by subsequent owners the specification may be far from the original.
Zak only used a Gp2 Mk2 in big box-arched form for one season alongside the Mk1 (same mechanical spec) then the rules changed and they had small arches, 1840cc wet sump engines, no rear links, narrower wheels, 4 speed Ford g/box etc. Eventually dry sumps were re-allowed after many engine failures but the gp2 cars were eventually developed into spaceframe Gp5 over a period.
Hope that makes sense as I assumed you meant Mk1 and have just re-written!