The JZ engines are very "poor" compared to the silky smoothness of the M103 and M104 engines, The M104 I think is one of the best engines ever shoved in the bonnet of a road going car. The 103 is a bit primitive to the M104 but it has a smoothness, sound and feel like no other engine like it.
Was this choice more because of repair technician qualification? - Common repair procedure for toieta in Pakistan is shotgunning scrap/kabli parts at the car.