Still seems like a lot of work to re-wood a touring into a runabout body.
Agree that just re-attaching the back seat clip of a touring, onto the touring front part of that '25 would be a rewarding and better result.
Tourings are a lot of fun.
To make a runabout, you have to reposition the top prop irons from a rear of a touring anyway, as the front section of a touring does not have irons in the body to affix a top. Unless you are making a very non-stock looking body runabout, then perhaps go for it. Still, the amount of grafting as you imagine, using new pieces to cut into old touring metal just isn't easy, the curves and radius don't mate, the rear door opening of a touring won't work with a runabout front door, all in all a real challenge unless you have to do it for some reason beyond me
A more straight forward attempt can be done with the
all-metal Improved Model T bodies ('26-'27), the metal subframes and metal can be welded back to almost replicate original contours.
Here is a '27 touring that is cut off, and the owner grafted the '27 runabout front seat rear tub to the '27 touring door frame where the rear doors latch, result is nice looking, the rear deck then becomes a truck bed. With more work, perhaps the whole tub of a '27 runabout could be welded on, and then fit a turtle deck too. No wood involved, just sheet metal working and welding skills.