Depends on who works on the car bro.
We have successfully gotten overhauled few EGs and EKs. No issues post overhaul. Car's kept running till the owners sold them off.
Anyhow I guess the issue here is mainly that you are unable to find the right mechanic. Please check with seniors pakwheelers in your city for guidance in that front.
If all else fails and you still want to go through with the swap. My suggestion would be to go for the complete package (engine, ecu, uncut wiring - without gearbox).
Or you could experiment in line with the "warranty" given by your mechanic on swapping just the d15b assembly without issues.