392 or 345 Hemi?Do both fit and A Body engine bay the same?

I just came across a 392 hemi truck motor with 32000 miles on it for about $3000. I only know what I learn from those who have done the swap.i thought it might be a good buy . I have a 70 charger rt/se without the original power train. I was thinking it would be a good fit , but I think there is to much different.