I've re-wired my Jimmy with a late model universal harness and don't recall the original fuse layout. However, here is a link to some wiring diagrams that should help.
http://67-72chevytrucks.com/vboard/s...d.php?t=185856
Since you've never had it going you need to start at ground zero. The absolute first step is to see if you have 12v at the coil. If you do, check to see if the coil is firing by attaching a timing light to the coil to distributor cap wire, hold the trigger, and crank the engine. If the timing light doesn't blink then the coil isn't firing. If the coil is firing, then check each cylinder in the same fashion.
If the coil is not firing make sure that all of the wiring in the ignition circuit is correct. Usually it's pretty easy to tell if someone in the last 40 years has done some hacking to the wiring. If something even seems out of whack, make it right. A little re-wiring can go a long way.
If the coil is firing and the distributor is not check it out real good. Wiring, rotor, points, etc. as I described before.
Now, if everything checks and you're getting spark but the motor still isn't firing then you've got another problem. If that's the case you need to check the fuel system first then suspect the ignition system again. Distributor could be 180 out or the timing could be so far off that it won't fire. Lots of other stuff too but we don't need to speculate just yet. Find out what IS working then we can work on what's not working.
I'm not a fan of just throwing parts at a problem but I do agree, since you're going to be doing all of this ignition work it's a good time to upgrade to an HEI. Another option would be pertronix or an aftermarket complete ignition. I run an MSD 6A box and Pro billet distributor on all my rides. Can't say enough good stuff about this setup, but it's an expensive route and quite honestly over kill for most applications. Looks good under the hood though.