I've got the Coopers STT Pro 10.5" on mine without power steering and it's not too bad. It actually made the steering lighter then the AT's they replaced.
I think from memory the screws mounting the tail lights to the bar are the earth, pull them out and clean em up including the threads and nuts etc....get some bare metal contact between the lights and the bar.
Double check your earth's, I had a similar problem when my blinkers would blink once or twice and then stay solid. They started working again when I cleaned up (wirebrush and sanding to bare metal) the earth's on the tail lights...40 years of mud and crud build up....
That was on a 1975 FJ40.
I ran into the same issue once with my 351c when replacing the points in a Mallory duel point dizzy, found one of the wires/connections for the points was barley touching the inside wall of the dizzy. Bent it back a little and she fired right up.......I know this is for points but maybe...
I did mine last year and I also dont recall any torque specs in the fsm...and I've got two of them. Just snug it down nice to where it lines up with the cotter pin....or split pin like we call em.
Had that happen to me once, found that one of the wires connecting the points was touching the dizzy wall...just had to bend the connection it in a bit and then she fired right up. Not long after that I gave up on points and put a Mallory unilite kit in.....runs so much better now.