Hi and welcome to the club.
It looks like some good work has been done and some original thinking.
There are a number of things on the 185 which limit the boost that can be run to stay reliable.
The headgasket is one of the main weak points and resulted in the death of many 185's as the garage bill for changing it was typically approaching the value of the car. The usual trick is to use the steel head gasket which is standard on the st205 as these are cheap as chips.
The intercooling on the air to air versions is terrible. The water chargecooler use on the CS/RC version is much better but still not ideal in it's standard form.
It seems the above two have been dealt with.
The next limiting factor, mechanically, is the standard piston. It is generally considered that 1.2 bar (fuel cut limit on a st205) is about the safe limit with these. If it were me, I would have swapped to forged pistons while the engine was apart as the cost is no higher than the standard ones. That is unless I was intending it to be a high milage road car.
The other limiting factor on the 185 is the whole engine control setup. The injectors are only 440cc as aginst 550 on the st205. These will probably reach their limits by 1.2 bar of boost. The earlier 185 ecu's (most of them) have a lower (0.8BAR from memory) boost limit. The other problem is that they are normally mapped very very rich as safety margin for the poor intercooling.
There are many options for ECU, each with their own merits, accoring to the planned usage for the car. Either a piggyback to retain the safety features of the standard ECU but tweak the mixture and timing or a full aftermarket standalone. This subject has been covered many times on here so worth having a dig around in the modifications section.
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If at first you don't suck seed, try drier grain.