Jobbob,
More details for you. 66 Signet is still an a-body, not sure if upper console plate & related parts are the same as later years but this is what I went through.
AMD factory shifter bracket (I chopped off the upper 2/3rds of it). Rear console bracket on the left.
I mounted console into desired position with front & rear brackets attached to the floor, and the B&M sitting under it (upper console plate just sitting in place), then basically held the shifter off of the floor into position & marked/measured the required mounting height at its base. This was done with carpet removed, and used the same method to mark my carpet for cutouts & location of console brackets beforehand. PITA to do by yourself, an extra set of hands would've been very helpful.
I transformed the unused upper section of shifter bracket into horizontal mounting plates with studs (shown in my original post above).
Made small holes to mount brackets to floor with sheet metal screws while mocking it all up, before welding
brackets to trans tunnel, in case I had to make any adjustments.
Shifter sitting on my re-fabricated bracket. Red pointer is of no use & had to bend it downward for clearance anyway. 2 small drill dimples on the right edge of gate plate are locators I made - The indicator housing mounting studs of the upper console plate almost rest on it at these points.
Shift indicator housing - had to chop off the lamp housing section and part of the rear guide tab for the gate slider.
As well as scallop the center section for clearance to the shifter's ratchet mechanism. I did not modify the upper console plate at all, only the shift indicator & ashtray housings.
Shifter needs to be set up pretty close to bottom of bezel, or there won't be enough clearance in the gate opening for full fore/aft travel. The only visible mod from the topside is the slot I had to cut in the gate slider.
I also fabbed a sheet metal bracket that sits flush to the bottom of shift indicator (where I chopped the lamp housing) - to the top side of this bracket I attached an LED strip for the shift indicator.
Ashtray housing - had to cut off part of the gate slide guide tab for clearance (shown in above post). What I'm calling the "gate slide" is the black flexible plastic piece that shifter stem goes through & moves fore/aft with shifter.
All welded in
Some trimming at rear of shifter - mounting tab for the original B&M plastic "console". The rear of the plastic gate slider was hitting it.
Functional with cable attached - hole for cable is directly behind the front console bracket. I think it was a 4' cable & was the perfect length... Went around upper passenger side of bell housing, downward & across the bottom of bell housing to driver's side. Used heat shield sleeve & attached to dust shield bolt with a clamp style retainer, plenty of clearance on headers.