Stroker motor genius needed....

Here's what I have....421 stroker, built by reliable builder, targetting 700 h.p. This is my third season with this motor, but really only around 60 passes. Dart block. The motor is in a '71 Vega....ran 9.64 last season. Over the winter, I lightened the car from 2600 lbs. to 2300 lbs. changed the carb from 1150 to 1090, and here is the big one.....changed the oil pan from a Canton with wide bottom to a Milidon with straight bottom. This was done for header clearance. They had always been right up against the pan, adding to the oil temp. First time out this season....the car lost 6 mph, and ran 10.00....and...get this...I had previously crossed the lights at the end of the quarter at 7600 rpm....always....very consistent. This time....over 8000!...and the motor blew the breathers out of the valve covers ( tubes going to headers for pressure release)..and blew oil all over the engine compartment. I'm thinking broken rings....somethiong really bad, but no indication of this before. I take a compression test, and all cylinders are between 150 - 180. Is it possible that using this new oil pan is the problem? I've heard that stroker motors need a wider bottom pan, but never even considered it when I changed pans. If this is the case, have I done some damage making 2 passes? Thanks for any available input. The motor fell short of the 700 h.p. by the way. It is making around 650......13.5: compression.