When the pedals are properly located in the earlier frame, there is still about an inch of offset in the clutch linkage. Some of this may be contributed to by the fact that the 35-38 pedals mount on the engine side of the frame, while the 39's mount on the oposite side, plus differences in other dimensions.
Spadaro is right, but finding a 91A arm is not easy AND trying to "harvest" one off another transmission, especially if it is still in the chassis, isn't easy either. Removing the existing arm is also a challenge. Making a linkage that is bent into an offset of the one inch will usually solve the problem and still allow for adjustment. I believe that the 91A lever might be a little longer than the 35-38? and have more of an angle leftward??? - have to go look... This will make the ratio/leverage/pedal travel a little different than a "true 39" but it seems to work ok from my experience.
It has been often stated here on the Barn that when installing 39 pedals in a 35-38 frame (they are not appropriate for 32 or 33-4 - too much butchering)
that "one hole lines up". I have found that to not be correct...and following that plan results in the pedals being out of the ideal correct position. Because
they are mounted on the angled x member leg, if they are installed too far forward, they will also be too far to the left, and if they are installed too far
rearward, they will also be too far to the right. In the case here, there is more
clutch linkage offset, so they might be too far forward?
I have a frame section for a 39 from which I made a template/pattern that can be used to drill the proper holes in the proper location AND to make the proper
cutout in the frame without compromising the structural integrity of the frame. (I have seen cases where someone whacked and hacked the frame (using trial and mostly error) so much that when either pedal is pushed, the
frame actually twists.) I can send a copy to anyone in need in exchange for a little "lunch money" to cover my costs.
Even when the 39 pedals are properly located, there are still issues with clutch pedal arm clearance with the frame, and location of the pedals in the floor. We
have all seen cars with 39 pedals where the pedal arms have been "adjusted"
and the pedal stems are "whopper-jawed" in the floor because the stems are
no longer perpendicular to the pivot shaft. This condition then results in the need to have an elongated (sideways) hole in the floorboard, since the stem
starts out in one place, but moves sideways as the pedal is depressed.
There are alternatives to installing 39 pedals to do a conversion that does not require any butchering, as the original pedals (and mechanical stoplight switch) are retained, along with the original clutch linkage, AND no need to
move the battery (35-36's) or to cut a hole in the front floor to access the
MC filler cap, and no need to rework the pedals - so they still fit the original floor board and function and appear as they always have. (and THANK YOU Bruce!)