All depends on budget.
If you daily the truck, I'd say get a junkyard engine block to build unless you can afford to not drive during a build. There is no "bigger engine", just more built or stroked. Any 5.2 or 5.9 will drop in.
You can try building the engine inside the truck but that's a good bit of work. To get the "max power" out of the engine - well it's an opinion. I personally think strokers are the best option for N/A. If you want to go boosted you're going to need forged internals to do it reliably. I think you can run low boost on the stock internals. Not my area of experience.
You can safely boost on stock bottom end to 15 psi. After that the Pistons explode. The valve train is another story and would require at least some modifications to make any serious improvements in power.
As far as engine swaps go op: it is possible to swap a hemi into these trucks but it is a very tedious and custom job. I've only ever seen two trucks with hemi swapped and both required significant modification to work right. A **** ton of people always say that they're working on a 1500 cummins swap (this was also me at one point) but honestly, most of these people don't realize the amount of work it takes to reliably build a 1/2 ton cummins. You'll have just as much if not more money in a cummins swap than you would for a hemi swap and you get less power for it.
You could always swap in an ls motor. But if you do, don't come on this forum. We're Chevy haters around here.
