If the rigging
is bundled together and still attached to the mast
The aft side of the mast
will have a track or a groove for the mainsail
to go up. All the rigging
will be attached at the top of the mast and will be in the proper position when raised.
If it is not still attached to the mast then you have a problem.
There will be 2,3 or 4 short wires that are the lower shrouds. From looking at photos I could find there are double lowers on the boat and they are symmetrically placed fore and aft of the mast so there should be 4 of them exactly the same length.
That should leave 4 longer wires.
Given that the rig is 15/16ths fractional and from inspecting a line drawing the back stay should be a bit longer than the other 4.
That leaves 3 wires. If 2 of them are exactly the same length and the 3rd is different, the different one is probably the forestay.
Often a forestay is one size larger (+1/32") than the other wires to compensate for anticipated wear by the jib
hanks. Because of the small size difference you will not be able to see the difference. The swagings/terminals at each end may be marked with size. If not get a micrometer. If you don't have one or can't borrow one, then lay the 3 wires out next to each other on a flat concrete floor. Put the one you think is the forestay in the middle and lay a straight edge across them and see if they are the same diameter. IF you can rock the straight edge back and forth at all then the middle one is larger.
Also because of the wear of hanks on the forestay it may be shinier than the other 2.
If there is no difference in size or length then it really doesn't matter then it really doesn't matter which position each stay is installed in .