Without breaking the bank, you can easily get over 400 hp out of your 360. I'm rebuilding a 360 magnum to swap into my 84 dodge so I can tell you everything I've done so far
1. You're going to want new heads. Stock 360 heads are notorious for cracking, plus they don't flow. Here, take your pick:
Hughes Engines
Also I would get some ARP head bolts
Edit: you don't NEED new heads, everything I've read up on just suggests you get new heads, but if you're getting a more aggressive cam then you might want to
2. Get a better cam, call hughes engines and talk to dave, he'll tell you to answer these 19 questions, or at least know them, or most of them.
#2---Choosing a Cam
3. Depending on the cam, you're going to need to get springs to match. You don't need to run roller rockers either unless you really want to spend some $$$. You may also need to get a torque converter to match, but that just depends on the cam, like I said, talk to dave.
4. Headers. These are what I bought without breaking the bank:
http://www.summitracing.com/parts/sum-g9045/overview/make/dodge
5. Intake for carb, same exact one I bought.
Small Block V8 Mopar Crosswind Intake Manifold Satin
You don't need the edelbrock RPM air-gap, it's going in a truck, not a drag car. Save yourself some $.
6. The carb.
Summit Racing has a huge selection here, personally I'm going to get an edelbrock 4 barrel 650 cfm manual choke carb for my truck.
7. Check this kit out: pistons (with rings), oil pump, all the bearings (cam, main, and rod), plugs, timing chain, and gaskets.
Engine Rebuild Kit 1993 2001 Dodge Magnum 360 5 9L V8 | eBay
Any other advice, this site will help:
Magnumswap.com - Your source for Dodge Magnum and Mopar engine swap tech.
Here's a good article aswell:
How to Add 129hp to a 5.9l Mopar Magnum - Engine Buldup - Hot Rod Magazine
Edit: You're probably going to run into a lot more problems if you get rid of FI. Your truck has it already, I'd personally just keep it. I know for my truck I have to get a custom ground cam with an extended snout just to run the mechanical fuel pump, where they might have one already made to your specs for cheaper. Click here:
http://www.hughesengines.com/TechArticles/6hughesfiairgaptechtestimonials.php
Also, you're probably going to want to upgrade your gears to something lower, just remember to change both to match if it's a 4x4.
My .02 cents, keep your 360 magnum, going to a different motor is probably going to be a huge pain. You know your 360's going to work and everything is going to fit and match up right, just upgrade parts on it and you'll have a ton of power and torque
And like I said, this is just everything I'm personally doing, you don't have to listen to any of it, I'm really not an expert