Talk to Paul at Don Scharf's Automotive. I recently bought an 01 motor (8,000 miles on it,) out of a roll over 01 gts. He guaranteed the motor for 6 months. I had him send it to Arrow racing in MI. The replaced the rod bearings, air idle motor, installed the correct 708 cam, check the whole engine out, and dyno'd it to make sure it's all good. Paul and I easily came to an agreement that he would pay for it all (minus the dyno run; my idea; I thought that would be fair,) and fired me out the check. I've dealt with him before on a front bumper cover, and he is more than willing to make it work no matter what. I've dealt with him since, regarding the valve covers being scratched a bit, and he's sending me brand new ones in the box no charge. The front half of the exhaust is different on the 01 (tube headers instead of cast manifolds) he sent me the whole front half of the exhaust out of an 01 (band clamp style as opposed to the 2 bolt flange style,) so I could use the newer stock tube headers, and it will bolt right in. Again, no charge! He doesn't even ask for my older parts back! Great guy! I wouldn't look any farther than him! Any questions; just ask!
I bought my 510 short block from RSI. The price was fair. $7,500...and no core. It came with new JE pistions, Manely rods, rings, coated rod and main bearings. I may have left somethings out as it was a long time ago.