Low 4-C to 4-C is 18.14x
4-C to High 4-C is 5.59x
So Low 4-C to High 4-C is 101.4x
100% Freeza is 40x Post-Zenkai Base Goku so at a minimum 100% Freeza should be 2.5x from High 4-C.
I don't know how power levels are gauged totally here but if you go by Goku being 3,000,000 and 2nd Form Freeza being 1,000,000 you could easily reach 100% Freeza being 120x 2nd Form, which should put him above baseline High 4-C.
Alternatively if a solid argument could be made for 3rd Form having a similar or greater boost to 2nd Form you could also argue for 100% Freeza being around baseline High 4-C.
Given the gap from High 4-C to 4-B is around 715x I could see 4-B becoming even more consistent
maybe some potential for 4-B Grade 3 Trunks? 715 / 10 already means he 'only' has to be scaled to 71x Freeza or Namek SS1 Goku to be baseline