I wouldn't bother with the 1.8 zetec in place of a 2L pinto personally, just put the bike carbs on the pinto.
The angle is not super critical, because thinking about it what does a bike do that a car doesn't ?, it LEANS when cornering, the carbs will cope ok with any angles a car can throw at them, when going uphill or downhill if the carbs needed a specific angle how would they cope with hills ?
The "specific" angle is no doubt just a certain angle that gives best clearance around other engine components.
tabetha