Sounds like you want a trail truck. Most trucks non racers call pre runners are trail trucks. Tons of info online about the conversions. The Ranger Station, Desert Rangers and Ranger Forums to name a few have more detailed info than here. This will start you out.
Ford Ranger V-8 Engine Swap
I've got a 4.0 in mine. I thought about a 302 or even 351 swap but decided to build the Cologne. A stock 302 is only a couple hundred hp. Were I to swap it would be a 2.3 liter Ecoboost. Take outs from LKQ are pretty cheap and the tech is modern. It's pretty easy to get 300 hp from the Ecoboost with minimal effort. More if you sink some dough into it.
For a 302/351 what you'll need to do will depend on what the core came out of. If you use a new Coyote crate you are over 400 hp easy. At a cost of about $10k new for the swap. LKQ has take outs for less. Many have done the 302 swap, it's not difficult. You don't have the grief of sorting out the street car Coyote computer to see what you need to get it to run. If you use the Ford Performance package computer and harness it's plug and play but maybe not legal for street use. At a cost.
If the donor came from an Explorer chances are you'll need a cam and head work or new heads. Eventually you'll probably want to re flash or replace the ECU. You can get them cheap, running, for a few hundred in many cases. If you work a 351 you can get it up to 300 hp without too much difficulty. For your app the hp/tq curve is more important than flat out hp. You'll need that torque to muscle through the dirt.
For suspension there are lots of choices. It will depend on what year you get. 97 and before are beams, after that are a arms. These days beam kits aren't that common but arm kits are. You can spend $3-5k on the front for a mid to long travel. I've got a gen 1 mid travel Camburg kit on the front that came with the truck. I did a Chevy spring swap/shackle flip on the back. Right now it's plain Jane Bilstein 5100s on both ends that came with the truck. The Camburg 98 plus entry level kit is only a couple grand.
Camburg Ford Ranger Edge 2wd 01-12 Entry Level 6.0 Kit | Camburg Engineering
Search around, plenty of solutions and ideas out there. People have been building these for years.