Leave the motor alone, they are indestructable. Take the heads off and give them to a machine shop.
If you wish my honest opinion it would be to have a pro do it. Just as you had a major problem with something that we would have diagnosed in the parking lot before it was off the wrecker, you will experience similar judgement and decision situations in doing this work that the wrong turn will cost a fortune.
If you just really have been wanting a project have at it. I would be surprised if it doesn't take you a month with no significant failures.
Bosch Master, ASE Master, L1
33 years MB technician