1978 Oldsmobile Omega

So I won't be worrying about electrical for a while but I'm curious about what I will need. My 78 Omega came with a chevy motor and I am putting in an olds 350...the old Harness is in nice shape but the fuse box looks... Toast. So if I go with a new harness, what is a good affordable option where I don't need to cut a lot. That is easily available in Canada. And what am I looking for in a harness?