I was going to put a newer LT1 in my third GEN but I’ve heard bad things and found a good deal on an LS3. I plan to get headers and a cold air intake and I just didn’t know if anyone has a link where I can get the headers especially since they probably need to be special to fit into my 85 IROC. I also know I need a special driveshaft and didn’t know if those are produced or do I have to have mine cut? Any tips or advice will be greatly appreciated! Hopefully this swap goes smoothly and she can hold the power!

 

The Gen-5 SBC Engines are by no means bad.
They are just less ideal for a Performance Engine.

The Fuel-System and Injectors are a high maintenance System, and will build-up large deposits in time that will hurt performance.
The Image below is from the wonderful GM (Isuzu and Suzuki designed) 3.6L V6 Engine (but is just as bad in the Gen-5 SBC):



When this bad, the Engine must be disassembled... cleaning services will not do enough.

Go with a Gen-3/ Gen-4 SBC if you can.
Or do the Gen-5 SBC but disconnect/ block-off the Injectors, and install an aftermarket Intake-Manifold that uses Port Injectors:

 

Vortec, he said LS3 . Still gen 4.

Time to start reading and read some more. Read all the swap stickies and 99% of your questions can be answered there.

 

There is a pretty large selection to browse at Hawks Motorsports website, https://hawksmotorsports.com/

Obviously some of the brands you can shop around for best price. Some of the headers are exclusive to Hawks and the more expensive stuff is really high quality (made by Stainless Works). I never see anybody using it but Kooks has some mid length headers. Speed Engineering is another "value" brand you won't see on the Hawks website.

Generally the higher cost headers are made with superior materials and have thicker flanges.

 

Thanks, I did read the part about the LS3, but I was referring to the beginning of the OPs Post: