The Vortec swap is supposed to be a nice one. Pretty much uses your existing wiring harness and all accessories with only minor mods to the wiring harness. As Eric said, the radiator is best put into the "forward" position by modification of the existing radiator support or you can buy aluminum ones that that fit "forward" without modification. This is required to clear the extra two cylinders you are putting in the front of the engine bay.OK I found motor mounts and frame mounts I'm going to use s10 2.8 mounts that are aftermarket ones that has no rubber in them. I been doing a lot of reading how to get my 5.7 vortec wired up don't look to be to hard to do. Sound like I have to get my ecm re flashed or get it re programed.
Which radiator and fans to use is highly contested. I started out with a swap radiator from Superior with two electric fans and a shroud. Wouldn't cool my 383 on the street. Went to a 7-blade flexalite metal flex fan and built a full shroud from a Summit kit, and that was better but still wouldn't cool on the street. So bought a new radiator support and cut it up to install a 1985 Corvette radiator from Jags that Run and built another shroud. Still wouldn't cool on the street. Finally went to a Taurus 2-speed fan and shroud, along with an electric water pump. Still wont' cool on the street, but I don't care so much anymore - only been racing the vehicle for some time now and it's turned into more of a racer with the door bars to climb over, and the fuel cell in the bed - but now I can cool it down between rounds. I really think those single core radiators Jags that Run recommends are for the birds. I bought their book and did everything that they said, but just can't cool my particular engine, which is 405 to the rear wheels as of last Winter. It just keeps going up and up the longer that I drive, even at speed with the Taurus fan on high and I have no inner fenders - so I really don't think I have an airflow problem. If you are making less HP (and it seems you are talking stock motor), then you probably won't have nearly so much problems with cooling unless you want to retain and run the A/C. In that case you will need to move the condenser way up front. People have done it.
For a swap without motor plates, the 2.8 frame mounts and the adjustable mounts as sold by Jags that Run or Transdapt, or any other number of sellers that require the 2.8 frame mounts are the way to go. Note that they have two height positions. Putting the motor high in front will clear the stock pan, but will give you an inappropriate drivetrain angle (trans pointing below the rear diff). This will be even worse if you have lowering blocks or springs in the rear. However, putting the front of the motor in the other holes will require you to cut off the lower part of the mount and use an aftermarket S10 Swap oil pan. Sorry but that's the only way to get the driveline angles right unless you build your own mounts and put the engine so far back that the oil pan will clear. But this causes problems with trans tunnel and header (to a-arm and firewall) clearance, and of course you need to modify the driveshaft because everything is sitting back further. My advice, just pony up an buy the Milodon S10 swap pan and oil pick up. You'll be money ahead and glad that you did. I use the Milodon pan with the engine mounts in the upper holes with the ears cut off. NO beating of the trans tunnel, Headers actually fit without rubbing on the firewall or frame (I have had both shorty's and now have fenderwells on it) and don't get crushed by the a-frame like the ones that were on my vehicle when I first bought it. If you lower your rear 3", you can use a 3/4" spacer from Jags that Run above the trans mount to keep the driveline angles correct. Also be aware that the swap mounts position the motor about 1" to the passenger side, but I believe factory is also there as a laser pointer on the trans output shaft shows that the tranny points exactly (right/left) below the pinion yoke.
So yes, the radiator setup, engine mounts, and exhaust are the critical things in a S10 swap. they all have to work out.
Good luck with yours.