To be honest I would put the boost back to standard, and leave it like that until you have a lambda sensor (wideband) fitted, otherwise it could not end well.
if anything the over boost sensor could be saving any damage being done at present, unless it has been correctly set up?
The actuator will have a preload set on it from standard. When you remove it and the waste gate is fully shut, and you hold the actuator rod up against the lug it fits on, the arm is usually half a hole to a hole too short (if that makes sense?). Any more and it could cause more boost. With the boost set to factory setting, I think the needle should go to the '0' of 'turbo'on the OE gauge.
Check the vacuum/signal hoses from the carb to the actuator, and see if any bleed valves or restrictions have been fitted, and that they are in the correct place. There's a good thread on here with standard engine bay pics, to help determin they are plumbed correctly.