The main thing is to not get into a hurry. Take your time and plenty of break in lube.
It doesn't take long to put together when you have all the parts. Try not to start till you have all of the right parts. Then do alot of research on the web.
I did this when I put my 455 together without a glitch. I've only done a few motors, but what a joy when it's done right. Recheck everything before you go to the next step.

(Nothing you can do that can't be done). John Lennon