Last night I had a go to see if I could make a JR fit to that Buccaneer 240.
Regard the shown result as an early draft.
I let the mast (or tabernacle) go through deck 1.27m aft of the bow. To get the CE half-right, I had to make the sail as a broad low-AR sail and even rake the mast 2° aft to get a decent halyard angle.

The shown sail will make steering downwind less than ideal. I guess I would have installed twin rudders, shaped as Karlis Kalnins did to the single rudder on his Otterbelly.

Ideally, I would like to fit the mast with no rake, somewhere between the shown position and point A, but that depends on what the interior will accept.

The good thing with this suggested rig, is that one gets a big sail area on a short mast. I have made the distance from deck to boom tall enough to make room for a tabernacle.

This sail has actually been picked from my stack of Johanna-style master sails, and is a 1:1 copy of the one with AR=1.85, only with the lowest panel removed.

Have a look.

Cheers,
Arne

(Full size diagram in Arne's sketches, section 7)

Maybe try searching for Otterbelly. I think there are some articles in one of the JRA magazine issues (Issue 74 maybe).... maybe a BOTM too. At one point I was looking at a 26ft Buccaneer that was also stripped out but did not have the resources at the time to move it. (they ended up taking a chain saw to it) I'm glad I didn't get it though. I really don't need to spend my time doing an interior rebuild as well as a rig change. The rig change will already be enough.... along with regular maintenance but at least we are already using our Cal29.

Good luck with the rebuild, hope it goes well. The Otterbelly ended up with a new rudder too, if I remember correctly.