I think that some Volvo entusiast/repair shop(s) were inclined to take whatever bodies they came across that were in good enough condition to merit 'restoring', enough to create a resaleable car, and if it was an automatic, they'd work with that. Imagine that for cars of this age, most likely, automatics were more likely to be purchased and driven and cared for by an older inital buyer - probably those bodies were more likely garaged, more carefully maintained by a mechanic, etc. And when they went to sell them or trade them in (I think this one went through Svensson's in Berkeley Ca.) these shops would end up with automatics, swap in an M40 (more saleable) and put them back out on the road.

I didn't seem to notice the pedal problem, and I have large feet.

Were ID plates riveted in or screwed in with tiny phillips head screws? This one is identified as auto by the 133461 number. Where are the tunnels larger? overall, or at the rear where the BW35 would sit?
Is there any problem supporting an OD to a previously automatic equipped car?