i use to run a 1.8 zvh with standard zetec pistons ( flat top ) on ke jetronic it made 264bhp and 286 foot pound of torque on a stage 3 t3 , @ 28 psi
ported polished head , kent 35k cam kit . erl water injection .. standard inlet and exhaust manifolds !
with a modified metering head , a bosch 044 pump, this was a cheap budget built engine my own and lasted over 5 years of good daily use .
if the water pump adaptor plate is good quality and done correctly with the surface of the block machined true they are no problem at all and imo much stronger than a standard 1.6 cvh !!
without the horrible tin sump issues too !!
have you tried unplugging the cold start injector on the back of the inlet and trying to start it ?