Take a look at this link,
http://www.chevyhiperformance.com/te...ams/index.html
I have one of these with very low miles, and I'm planning on building it pretty much like the one in that article. My present 406 is worn out, so I'll throw one of these together while I decide on building a better 406, or moving on to an LS based engine.
Unfortunately, L31 blocks are not machined for mechanical fuel pumps, so you'll need to set up an electric one if you haven't already.