They don't mention compression. But the pistons are a flat top and not dished, so at that bore the compression should be pretty decent.
FYI, a 4-5/8" stroke is needed to reach 131.
S&S 131 Top End (https://www.sscycle.com/feature/performance-kits/131-cylinder-piston-kits?utm_medium=email&_hsmi=102176706&_hsenc=p2ANqtz-86UnHALSY4VlC57pTI9aXCoXWsjdkwzz_WLV6EE6JiObikjR0jV927CEVfv8lPFoYvxiy3Ny_FVKRLdvABHUdubK4hqQ&utm_content=102176706&utm_source=hs_email)
If I have to split my cases, I'd just assume bore them at that point and go with a 4.5 bore. Why limit yourself? You're not adding that much more in cost but getting quite a bit more displacement.
A 130 from a 114/117, top end job
If case boring why not retain the 4.5 wheels, reworked and go right up to a square 143"?
A 128" S&S cylinder kit surrounded with the proper components can show 150 hp, and mid-upper 150's torque.(our Facebook)
A 131" with same/same 3/3 more?
Lot of dough for that gain?