I've always known I should have documented this......
This assumes two things:
1) you want the drum as low as it can go to the deck
2) you have the original forestay setup, with the 2 SS tang plates
Because the fractional 235 has no turnbuckle in the forestay, you need to add one per the FF2 install manual. It needs to be open body, swage/Tee ends, with the swage designed for 4mm 1x19 SS.
Open the turnbuckle 1/2 way and measure from the center of the Tee tang hole to bottom of the swage fitting hole (A). You can also measure to the swage end and subtract the depth of the hole.
If on the existing forestay the pin is not in the TOP set of holes in the tang plates, measure the center distance from the current hole to the center of the top hole (B). If it is in the top hole, B=zero. This is done because the FF2 will be mounted at the very top of the tangs. Drawing assumes 4th hole, which is kind of standard.
Add A+B, and cut that much off the bottom of the existing shroud. Swage on the turnbuckle.