If the lifter bores are not gouged too bad, you can clean them up with a brake cylinder hone.

Don't feel like you are the first one to have one of those pickups fall out, DOH!!! It happened to me with my 400 SBC in a bracket car and I spun a bearing. Pulled the motor, flipped it over and pulled the crank out, had it turned and replaced the rod bearings and put it back together without even pulling the heads. When I sold it, it had over 350 runs on it and was still going strong.

Pat