I have owned 2 of the older 5.7 hemis, an 03 and 05. I currently have the Eagle motor in my 09 Ram. Neither of the older blocks had noticeable wear in the bore except one cylinder from a broken ring Even with nearly 100k on the block there was no ridge to be felt at the top. A block with 120k should be very serviceable.
Be careful on the overbore. Some of the early blocks were known to be "meaty" and some were very thin with noticeable core shift. With the kind of power you are wanting to build a sonic check is a must before you go any further.