6.0 Swap dreams, ground me some
 

If you are just looking for a little bit more power and the sound factor then i would look into a 5.3 or 4.8 to swap rather than a 6.0.
around me a running 6.0 goes for $1000-$1400 for the engine alone while you can pick up a 4.8 or 5.3 for $400-$600. Next you will have to see what accessories you want to run. Im running corvette accessories on mine for more clearance but these ran me about $1000 for the full setup including new alternator, PS pump, water pump and balancer.
the most expensive part after the engine is a harness and tuning for the engine. A harness can set you back $800 or more If you buy a custom built harness that can just plug into your truck and the engine will run like 4.3 with all gauges working like factory. Tuning will run you around $300-$400 for a good street tune or dyno tune to make it run right.
To put a LS into a 4x4 you will need a special oil pan because the traditional holley or hummer H3 pan will not fit, but a couple companies make a pan for this with an oil filter relocation.

Next you will have to look into a transmission. A good built 4L60E can withstand a 4.8 or 5.3 but a 6.0 may kill it unless you spend big bucks to have it fully built but these run $2000+ for just the trans and another $500-$1000 for a good lockup torque converter. For the 6.0 you should step up to a 4L80E which is what came behind most of the 6.0s from the factory with a few exceptions.

One of the weakest links with you wanting to run 33s or 35s and a V8 will be the differentials especially if you have a 7.5in rear diff.

There are a ton of other smaller items that add up like driveshaft modification, electric fans, engine mounts, power steering lines, battery cables, heater hoses, fluids, plug wires, fuel lines, transmission cooler, trans mission cooler hoses Transmission cross member, etc

I agree, got with the 5.3 but skip the 4.8. If you are going to through all the trouble, go with the 5.3. It will have more than enough power for a Blazer plus it is more reliable than the 6.0.

The 5.7 is a great engine and a much easier swap, but, and that is a BIG BUT, the 5.3 has more power, better mileage and less emissions.

Here's what I'm basing my build on, my 2003 S10 crew cab is a going to be my daily driver so it has to be dependable and I plan on occasionally hauling a 24' tri-toon to the lake with it. I have an L33 5.3 alum.blk. 310 hp (about 375 hp gross). No increase in the frontend weight but plenty of torque to pull the boat. You need to consider this, if you build a mega hp engine and intend to drive it hard you're going to have to upgrade your drivetrain...transmission and rear end. Like some of the others said you can get loads of hp out of a 5.3 which you can get cheap. Add a set of 799 heads for about a third the price of a 6.0 leaving money for the other upgrades or swap cost.

I wouldn't waste your time with the 5.7 vortec swap I have it in my 2wd blazer and although it's def more fun, If you are looking at it from a performance stand point the 5.3 or 4.8 will blow it out the water, 4.8 would be fine IMO stock it will make more power than the 5.7 vortec and after market support is greater, I think it would be cool to go to a 4.8 bc when asked what motor it is and people try to correct you and say 4.3 you get to recorrect lol and show off.

Just keep your eye out for a 4.8 , 5.3, or 6.0 complete pullout make a budget and get after it.
Been looking the 6.0 does typically cost more but you can get them with 4L80e's as well

NO MATTER WHAT you will need a tune/ install the the motors which is going to run into the same stuff no matter what motor you run

also look at what parts cost that you may want to do.

I jumped back and forth between 5.7 or LS swap in my head for a while... Even started gathering parts and had some heads at a machine shop for a 5.7 I was going to go ahead and build. I ended up shifting gears (no pun intended) and went with LS instead, mainly because an LS3 fell into my lap :D but to be fair, working in the auto salvage industry, LS engines are MUCH easier to come across, cheaper, and make more power. Sure the 5.7 is proven, but so is the LS platform. You really can't go wrong with either as far as reliability goes. The 5.7 IS an easier swap mechanically and electronically (which is at first what had me turned onto it), but in my opinion the little extra work it takes to get an LS running in the engine bay of the S-chassis is well worth it in the end.

As far as trans, I'm going with a GM reman 4L65E that was backing a 6.0 in an Escalade. Be about as strong as a good "built" 4L60E, but mainly the reason I'll be going with it is because pushing 500 HP to my 200k mile 4L60E would certainly not end well LMAO and just like the LS3, it sort of "fell into my lap" :D