k frame dilemma

Many options.

Tubular K frame from QA1 will use 68-72 &73-76 idler mount that won't fit your 67 idler. This will mean a new centerlink and pitman and LBJ.

67 K frame is fine. Firm Feel have a great reinforcement kit to weld on. Easy enough. Hot tank frame first.
In the end I got a 68 frame idler arm mount welded to my 67 K frame, with 73-76 centerlink etc. Reinforced it with the kit. Have a borgeson box now too.