After I re-read the original question I realized it's in a longblock form already... I usually use the muratic acid if it's a bare block and the hot tank did'nt get it like I wanted...I'm not sure I'd do it with an assembled longblock...I put the block on an engine stand,plug holes, and start pouring...Let it cook for a while{until it looks like it's not doing much more} and drain it....You would'nt believe what comes out of a "clean" block...Turn the engine to a different position and repeat...
I'll have to check on what strength{there's different concentrations} I have in the gallon containers.. I just used it straight last time...We have to do this to our fishing boat every few years to keep the sea water passages open it really cooks the debris out...