I put a set of FJ 100 seats in mine. The good and bad includes:
attachment points closest to the console and front mount perfectly.
attachment points closest to the door and front mount in the existing holes, just need to be driled out and replaced with schedule 8 bolts, will need several washers to build up the mounting point, but can be secured well.
attachment points to the rear of the seats are the challenge, those will require drilling through the floor pan and I used a piece of steel plating behind the bolts to be sure it is was secure to the floor. Again, all new schedule 8 hardware.
Advantages, power and heated seats, nice headrests, arm rests, far more comfortable, lots of leg room.
Disadvantages, having to mount through the floor pan, eliminates center console due to the spacing, crowds the hand brake and had to make some slight modifications to make it more useful. Had to reverse the seatbelts (attachment points mounted to the floor behind the console area)
Safety, moved the seat slightly back behind the B post/column and further away from the dash.
Issues that could be (a) disadvantage(s): if you are vertically challenged, you will not be close enough to drive it. I am 6'1" and love the legroom, and have some adjustability if needed. I won't comment on my wife's anatomy but in case she had more seat to put in a seat, these will accomodate it! It does crowd the rear seat because it reduces the space between the front and back seats by approximately 3 inches from stock.
I have a few photos if you follow the link on my build, nothing of great detail but it will give you a look at what FJ 100 seats look like in a 60. I had these from a previous project. If I was buying something just for this rig and had nothing to start from, I would look for a set of seats from an extended cab pick up truck, or a convertable (seatbelt is self contained from the shoulder to the waist), leaving you with a measuring tape and trying to see which would be the best for the mounts there. One other word of caution, some seats have air bags in the seat, if you want them to hook up to after market sensors, may be fine but either way, I would keep that in mind.
Hope that helps,
Randy