Depends on what you want to do with the truck:
if you want to regularly tow over 6000 lbs, or you want to play in the mud/hill climb all day, or you are building an offroad only truck, then a 454 may be what you are looking for, but be prepared to 1) cry at the gas pump, and 2) pay a fair amount more for initial build.
if you are looking for a well balanced motor, that can do most everything you want, you will probably want a 350. they can be built mild to wild, and do most everything you ask of them
btw, that 1400 one on summit is lacking a lot of key parts, intake, distributer, all the accessories, water pump, etc... (see the "recommended accessories" tab) you will want to factor all that in when buying. However, that is a good mildly built engine, it will do most anything you want, but it is by no means a high performance monster
i see nothing wrong with a good mild 350, but you may want something different