'71 C-10 Power Brake Conversion: Brake Rod Too Short?

[71GreenJunk]

Hello, I'm converting my '71 C-10 to power brakes using a factory GM brackets and linkage. Everything is bolted up but I've got 1 problem, there's still about an inch or a bit more between the hole in the brake rod and the hole in the pedal. My understanding is that I should be aiming for 1/4 inch but by the time I get there, there's hardly any threads left, way too few to trust. I'm not sure what I'm missing, wanted to get some input. Thanks.