Front torque box behind front wheel
next to front seatbelt anchor
rear torque box infront of rear wheel
over rear wheel beside shock mount area
behind rear wheel
rearmost frame rail ends

Here is a pic for a 69. Dave would this be close for a 67 ?    Bolt heads up though holes in the frame.

you might want to find the bumps over the bolts in the floor assuming your carpet and insulation are out drill some large hole with a hole saw able to accept plastic plugs a spray the heck out of the bolts before you go breaking the cages off the nuts its a real pain to fix after their are 6to 8 body bolt and two are really well hiden