I have the low deck wedge version of this block. Never had a cooling problem but I did flare out the return holes in the front of the block, (i have reverse flow cooling), As for oil return I opened the holes up in the valley & chamfered them & had no issues with the wet sump. Now I have a dry sump set up, I have a pickup at the back of the valley & to date, haven't experianced any problems. I'm no pro engine builder, I'm just armed with a dremel & did what I thought was necessary. Had my block for over 10 years now, running in the mid 800hp range. I would buy another block no problem.