Bruce-
No need to rip anything apart to get to the wiper motor but it will take some work. You need to remove the rear view mirror, the front window garnish moulding and radio speaker (it is attached to the car by the two mirror screws and two header panel screws). There are three wires attached to the speaker. Their placement should be already color-coded. You have four remaining screws to remove the header panel. Two plated screws and a small sheetmetal screw attached to the "A" pillar on each side of the header panel. Remove the wiper knob and the panel should come off.
Once off you should find the headliner is attached to a upholstery tack strip. No need to undo it.
As for the radio speaker, to the best of my knowledge all factory Radio speakers for closed cars in '35 were between the two visors. With the advent of the '36 the large speaker platform was deleted and the speaker was hidden behind the headliner. Open cars had the speaker integrated into lower dash radio unit.
Enclosed picture is my '35 speaker.
Hope this helps.
Tom