Re: $6,600 to rebuild Atomic 4? replace/rebuild
Good decision. You are going to get a lot of fun & satisfaction out of the project - a new engine will be a bonus.
If you haven't already, I strongly suggest you check out Porfin's thread about his ongoing rebuild of a Perkins 4108. Obviously the specific mechanical info will differ but there are lots of tips & tricks he is doing that will transfer to your Atomic Bomb.
Have fun, take lots of pictures and keep us posted.
I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.