If the return is big enough and the system clean enough it should never block, my brother had a smoking issue on a new turbo once, turns out there was a piece of plastic wrapping stuck in the drain, causing enough back pressure to leak past the seals once pressure built up.
The PRV in the oil pump should be sufficient to manage oil pressure throughout the system, the only thing that controls the pressure in the turbo is the size of the restrictor (in a ball bearing turbo), BB turbos require less oil pressure than a journal bearing turbo. Providing you have the right size restrictor and the right size drain gasket, you will have no issues.