You can't argue with the v-8 for cheap, easy horsepower. I prefer a 6, and they can be warmed up to perform just fine, but it's not cheap unless you have machine shop and engine building skills.
Hopefully you are planning on suspension and most essential the brakes as well. Very important if you are going to increase HP. You will also have to figure out proper tranny and rear for today's traffic and how you want to use it.
Just my opinion, but I like the 55-59 for your purpose. They look great all original or as hotrods. And hop up parts that fit are available from the junkyard or from parts houses to vendors that carry high end new stuff. I especially like the 4wd shortbox fleetside. I think the 60-66 look like crap as hotrods but good as trucks.
