I can get a complete dropout 4.8/5.3/6.0 with ecm, harness, and front drive accessories for around $600 the local junkyard. It's harder to find a 6.0 but I recommend it if you want a slightly better platform to start with. You can cut your own custom harness from the original one if you're ambitious enough and follow all the info on the lt1swap.com website. There's a ton of diagrams and pinout descriptions on that site and the creator of the site answers questions you have through email. I got my motor mounts from dirty dingo Motorsports and they looked and worked awesome. My last recommendation is that you at least do a cam swap when you have the engine out because if you don't, you'll want a little extra power later