Here's a link to an article that may help:http://www.13thfret.com/bridge-pins.html
There is a certain amount of consistancy among guitars of the same model and manufacturer.....but there are differences also. Pins that fit your J56SW
perfectly, probably won't fit another J56SW...perfectly
. There may be some differences in diameter amoung the six holes in the bridge on your model.
(When a company claims to sell pins that fit your model...the top of each pin...under the ridge and ball... still, under nornal conditions, has to be sanded slightly to fit each bridge hole properly.) The exception would be if the company sells a slightly undersized pin for your model. (that would be the measurement at the top of the pin shaft just below the ridge and ball)
I wouldn't recommend
slotting the bridge and going to solid pins (as the article suggests) unless you're a professional player and consistantly use the same guage strings.
You could have the bridge holes reamed (on your guitar) to match a set of pins that's being offered by Maurys Music...(size 1 is your best bet- 0.210 at the top of the shaft)
You could buy a set of 3 degree slotted pins (as the bridge holes on your J-56 SW are probably not tapered) and hand fit them yourself.... again... a size 1 is your best bet.