This is going to be long but I would like help.

Back in Feb this year I was running along and all of a sudden my motor shut down.
At the shop it was determined the #2 overheated.
I had the motor rebuilt completely all new psitons everything mechanically in the motor.
Got the motor back around march and was instructed to run 2 tanks of fuel double oil. The third tank motor started missing. Carried it back and was determined the voltage regulator was bad had it replaced.
Went back out and would not get on plane. They then replaced Power pack,Stator,timing base and voltage regulator. Took the motor out and it ran great for about 3 miles then blew again. this time it was the #5 top center of piston.
It was under warranty and replaced the #5. That was in May. Since then I have went through 3 sets of electronics I mean all. voltage reg, power pack and stator. Can have a new set put on and in about 2 hours the regulator will go out andthen the stator will melt the charge coil.
This last time we aere looking closer trying to figure it out and noticed the popit valve coming from the center water jacket to the left side had the black round seating plastic ring installed backwards. We turned it around the proper way.
My question after all I have been through on this motor is. I also have a low water pick-up on my motor Aparently the regulator is going out due to over heating. Water pressure at idle is 3 lbs and at speed 35-40 lbs. With the low water pick up can it not be giving me enough volume to cool properly even though I have plenty of pressure. Yes I have tried BRP and aftermarket components on this problem the same outcome. Please give me your thoughts.