to replace the RINGS< you have to drop the pan an pull the head.

you might as well replace the bearings while you are at it.

THe do rings and a headgasket figure $750-1000 in LABOR only.

10-15 hours from a shop.

Silversol is right, you are better off buying a longblock.

And if your motor smokes from OIL just re-ringing it may not fix the problem if the bore is out of round