Boost leaks, or your gauge could be faulty. Mine used to read 3psi out.
Pressure test the intake and drop the boost to minimum and see if it goes away. Some ecu's just don't like high boost.
Time for a tune?
I asked around, no-one I know with one Daz.
Why don't you just stroke the motor you have? Probably take less time than trying to mod the 30 to fit, and at least your lower gearbox bolts will fit that way.
Have you dropped the boost to see if it goes away?
Without a list of mods it makes it hard to suggest much. I would recommend finding the issue instead of throwing parts at it.
TD06
GTX3071
There are plenty of others, but your choices will change my recommendations. External gate and e85 would be the most important upgrades I could suggest you do at the moment.
Do you have access to an e85 pump? Where are you located? Are the police happy to ream you after popping your bonnet? Do you have yearly RWC inspections? etc, etc.
Not max power, no.
I will be running my new 4G64 stroker in on the dyno soon, aiming for 250-300kw at sensible boost. Then I will wind it up a few months later, just before I change the transfer case and diff I imagine.