[Zoomad75]

The big block or 6.2 radiator will fit, but depending on which one you use you need the right brackets to hold it off of the core support. Obviously, you'll need the correct shroud depending on the radiator you intend on using.

I went from the stock 350 radiator to a 6.2 radiator with my 5.3 swap. It ran hot in really high ambient temps at low speeds. On the road or off road. Now with 6.2 radiator installed the highest I've seen the gauge was 200 in 113 degree heat on the Mojave road. The rest of the time it runs at 160 to 170.

The 6.2 stuff is harder to find for the top plate, brackets and shroud. One thing to keep in mind if you move to the bigger size is your evap canister *might* be in the way. I've got dual batteries in my K5 and that 6.2 radiator is really close to the driver's side battery.