the tall geard 10 bolts are a pita when it comes to gear selection, espically the earlt 8.2 ring gear rears.
ive seen this spacer used a few times to install a shorter gear, one of them wasnt pretty. sheered the pinion in 2. but he was also running a 455 infront of it.
if this were my car, id run a 9". get the rearend length close and if its not perfect, make it so with rim spacing.
any rearend, regaurdless of suspension type will work, if the length is in the ball park.
spring perches cost about 20 bucks a set. cut off old brackets, and weld the new perches on. pay attention to the pinion angle!
to change gears in your 8.2 youll need that spacer, bearings and gears, thats over 275 dollars. if this is the route you choose, forget the spacer and install a spool. it will be a few dollars more, but both tires will be locked(remember this while driving in the rain)
a new rearend is your cheapest bet.