I though this would help people when choosing a donor.
“The lack of a catalytic converter is not an automatic fail in itself, but a vehicle may struggle to meet the required emission limits without one. Prior to 31 July 1992, a spark ignition engine is required to meet limits of CO<=3.5% and HC<=1200ppm. Between 1 August 1992 and 31July 1995, the limits will depend on whether or not the vehicle is listed in the current edition of the In Service Exhaust Emission Standards for Road Vehicles book ( currently the Ninth Edition) which all MOT stations are required to hold. If there is an exact match in this book for the vehicle ( regarding engine number/type, model, chassis no, etc. The exact requirements vary between manufacturers) then the vehicle will be tested to the limits in the book. If an exact match cannot be found, the vehicle will again need to meet limits of CO<=3.5% and HC<=1200ppm. I have looked up your particular model and engine and, as stated in your e-mail, this combination is not listed and therefore the vehicle would need to meet limits of CO<=3.5% and HC<=1200ppm. From 1 August 1995, the requirements again depend on whether or not the vehicle is listed in the Emissions book. As your particular combination is not listed, vehicles of this age would need to be tested to the following limits: Minimum oil temperature : 60C Idle (450 - 1500rpm) CO<=4.5% Fast Idle (2500-3000rpm) CO<=0.3% HC<=200ppm Lambda= 0.97 to 1.03 There is one possible exemption to the above requirements. If the customer can provide a letter from the manufacturer, quoting the chassis number and engine number of the vehicle, stating that the engine as originally installed could not meet the relevant UK emissions limits. In this case, the vehicle can be tested to the next lowest limit.” Hope this clears things up...
http://www.imoc.co.uk/forums/viewtopic.php?t=43072