Nah, don't kill the bastard [censored] - you want to make him suffer. Once you've got him you can rough him up real bad before you call the police, then explain in court that your truck is "your baby" and that this was a crime of passion.
Personally, I'm thinking that my blazer is getting a LoJack system (
http://www.lojack.com/). Not a bad idea to shave the handles and install a keyless entry either (although in a 71 k5 that won't do *anything* with the top off). As mentioned above nothing you do inside the cab, including starter/fuel kills and brake locks won't mean anything if they steal it using a wrecker with a wheel lift. A brake lock will make it much louder when they do (attempt) stealing the truck though, which might give you enough time to grab the 12 gauge and go for blood. A lojack system, on the other hand, will alert authorities to the location of the chop shop and hopefully bust everybody involved rather than just the guy getting the truck.
My blazer is going to get huge horns, I think it'd be a good idea to add a flip-flop circuit with a relay to the ign switch, and a cutout tied to a keyless fob. Hotwire truck, get started, then the horn is blaring at full volume until you can either disable horn(s) or someone with a gun (me) comes by with the keyless fob to turn off the horns and wound the silly bastard.
