Just some food for thought,
Depending on what you have things may or may not survive behind the 440, depending on how stock you are keeping the motor and how heavy your right foot is. I would assume you have a 9 1/4 rear and dana 44 front, if they have not been upgraded. These are known weak links when putting power to the ground. Also what tire size are you running? Anything greater than 31's to 33's will eat these axles (In my review of the posts) with any power run through them. Transfer case may also be questionable depending on how wild you are going, then driveshafts etc. Keep these things in mind when doing a build so you are not surprised when parts need replaced or upgraded. It kinda snowballs pretty quick and funds/parts can be tough to come by in my neck of the woods.
A teen (318/5.2L) or 360 can be built modestly and decently cheap and make considerable power, especially if you stroke it out. All depends on budget and willingness to identify exactly what you want. Big block does equal more weight/torque, which makes it harder on everything else down the line.
If you do swap it, which I hope you do and have some fun without hurting yourself or your truck too much, don't forget throw out bearing in the motor. Also you may run into some fitment issues and cooling issues depending on radiator, build of motor, and what brake master cylinder you have. I know these are some known issues when doing these swaps. Do a search on the website here and you can find lots of info for people running big blocks.
Best of luck,
Neil
