rebuilding a 6 bolt with 250 horse..... that will be ALOT cheaper than $8000...
finding a used 6-bolt with crank - $300
2G pistons - lets say $200 to be safe.... you can find them for cheap though...
1Gb big rods - if you find these, you are set... they go for around $500 I think....
Head - you can use the head you have on the car right now, and the manifolds, turbo, etc....
basically, if all you need to replace is the bottom end of the motor, you can do so for $2000 or so if you find all the right parts....... and then use the parts you have now for the top end.....
if you need to replace the top end to... it will probably be another $2000 or so for the head, manifolds, and stock turbo....
and then you have to get the motor swapped in...