This is my first build.  Going through the parts of my 1969 Russian underfolder I notice that there is no sight rail mount that would normally be on the left side of the receiver.  Did these not have them or are they just not included with any kits?  Can one be purchased anywhere?

I believe these weren't standard issue until the AK-74.  The stock tang on the AK-74 has the lower rivets about 1/4" farther forward than the AK-47.  If you use a 74 rail on a 47, the clearance notches for the pivot pins will be off and may prevent removal/installation of the pins once the rail is installed.  You can grind clearance for the pins and everything will be fine.  

The other option would be to use a rail designed for the AK-47 rivet spacing.  These fit properly and there are no clearance issues.  You can pick up rails from Tantal:

tantal.kalashnikov.guns.ru/bstmounts.html

or Ohio Rapid Fire

www.ohiorapidfire.com

Since you're starting with a kit, you can use a rail that attaches to the stock tang with the rivets.  On a complete rifle, you would have to remove one rivet or use a rail that screws on.

There are a few other sources online, but you'll have to do some searching.

Thanks for the info!

Here's the direct link to the ORF page.  I don't want to sound like a shill, but Todd is a decent guy to deal with and he does good work.  If you are considering this one, ask Todd which stock tang should be used.  Since your kit is unbuilt you can easily substitute a 74 stock tang for the 47 if need be.

rapidfire.targetweb.net/cgi-bin/store/agora.cgi/agora.cgi?cart_id=6055486.32249*ID24p6&p_id=00006&xm=on&ppinc=big