225 or 318

So I have the oppurtunity to get a 318 for free....I currently have the 225 slant 6....I am totally new to the whole build part of this...I am learning as I go....I have never done engine stuff before, but if you don't ever do it, you'll never learn...Now my questions

1.How hard is it to swap them out???

2.What other parts are needed to put this in my car??

Any other info or directions to something would be great!!!!

Thanks guys!!!