Yes its a new high volume pump - everything is new but the block. Went high volume because the machinist/ builder said he ran the bearing clearences a bit looser - something he suggested with a BBC.
I only spun the pump 500 rpm.... that does not seem like it would build high enough pressure to cause a relief valve related problem? I really am worried about the GM block to oil filter fitting and possibly that being installed wrong, but then again the filter ballooned up so it had some major pressure.
Going to double check the part number on the fitting - maybe they gave me a small block fitting??? (could be the same part#)
Worse comes to worse, then bummer off with the pan - damn.
Thanks again for the feedback - anyone with other suggestions I would be happy to hear them (but sounds like I have the solution) :|