Great engine - just that the sensible thing to do is to ditch the problematic LH system and throttle bodies and fit Mega squirt with Mustang throttle bodies.
Extract more bhp and have reliability with a simple system - and fitting a mega squirt system from scratch can be done for about 1500 gbp.
This is what i'm doing with my M120 fitment in the Brabus w126 SEL....keeps things simple with more power.