Help Sourcing a Radiator

[quick60]

I have a 67 GMC 3/4 ton 250 3 speed no air. I've been to Autozone, O reillys, and Culpepper radiator and they are all selling me the same radiator that does not fit into the support brackets on the radiator support. Culpepper says they cannot repair my old radiator its to far gone.

In order to get the radiator they are selling me to fit I have to notch the lip of the radiator support which to me looks like it will weaken the support.

Is this the correct method of installing a thicker radiator?

I would much prefer a stock radiator for that truck but even LMC does not have a radiator that fits the measurements of my original radiator.

Any ideas? I can send pics later for better clarification.