I have them for some Corbeau Targa RS's. I wish I would have gone with the baja's, but I thought I wanted reclining seats. The ones I got have the seat belt tab welded on, and they are adjustable with 3 height (by bolting on), but even at the lowest setting, the seat sits a little high on the pass side.
the prp brackets are like $20 each. why not just buy them instead of modifying the corbeau brackets. Give the guys at rock buggy supply a call, or PRP themselves. But are super helpful.
You putting them in an fj40? Should be an easy mod. You can even just take your frame over to a welder if need be and have them burn mounts onto the stock frames for the PRP brackets.