is close enough good enough?

[swizzlestick]

I'm building a 49 chevy on an s10 frame. I'm currently in the process of mocking up the body. ive got the cab mounts made and tacked in place but i'm starting to notice when it comes to the body nothing is quite the same from side to side. the truck I started with was in very good shape for an unrestored truck so i dont think its wrecked or anything. so when it comes to lining things up and comparing side to side whats good enough? i know i should be as exact as possible but is it more like get it close and make sure it look right by eye? or is it move and adjust until its perfect? (I know door gaps and stuff will need to be uniform)