Pretty sure the dizzy hold down is a 12mm. It's not difficult to get to, but a one foot extension on your ratchet makes it a bit easier to tighten when it's running. Standing over the passenger fender looking down onto the dizzy, you'll see the hold-down clamp, it'll be on the right. The fan blade is a bit too close to try to get a wrench in there when it's moving, unless you don't need those smaller fingers anyway...
The way I read your post, you are planning to drive the truck home? If so, I'd recommend bringing along: vacuum line (or loose screws to cap lines that might break), a couple of coolant jugs full of water, a good spare tire (or tire in can), portable battery booster boxes w/air compressor, gloves, roll of blue towels/red shop rags, 15 AMP fuses, turn signal/brake light bulbs, an extra set of points, an extra plug wire or two, a roll of duct tape, a roll of electrical tape, a decent blade to cut hoses/lines that might split, flashlight (I like the wind up type), can of brake fluid, channel locks, blah blah blah...
Don't trash anything you take out of the truck for the tune up until you get home. That old dizzy cap just might come in handy...
Also, if you don't have a chase vehicle/friend, make sure someone knows what you're up to, and what your planned route is. Just in case. Make sure your cell battery is charged/bring a charger with. Depending on the terrain/time of day you may also want some flares. I have AAA+ just for this sort of thing, make sure you bring your card with you if you have it, and make sure you bring proof of ownership papers. Some of the AAA guys can be really anal about that, as can the local constable.
I'd also recommend bringing some Sobe Green Tea and a bag of GORP....
Prepare for the worst, hope for the best. You can definately bring too much stuff with you for something like this, but I like to err on the side of not meeting 'Mr. Murphy'. If you bring it and don't need it, you'll probably need it if you didn't bring it...
I've done quite a bit of driving derelict cars out of the woods, but it's been awhile. Your's hopefully has been roadworthy recently. Anyway, it was always an adventure, and always took several hours longer than intended. Make sure to budget some extra time, being tired and stressed doesn't aid in creative roadside car repair...
I'm sure some of the other folks here will have tools to add.
Have fun
