Those 4 holes are to mount your clutch and brake pedals should you wish to convert to right hand drive. They are not shown in Teri Ann's photo as her car was a later car. The other hole is some of the same RHD.Thanks NutmegCT. The holes I pointed out are not identified in any of the images in the link you provided. The cluster of four captive nuts on the right side of the image I provided are not visible from inside the engine compartment and are located on the outer fender side of the inner fender. Clearly they are there for something to mount to inside the passenger compartment. The same goes for the other two mystery holes.
I checked TeriAnn's site as well as Piggott's book and they're not referenced in either resource. I found one image in Roger William's book on page 51 that shows the cluster of four holes in a replacement panel but that's all I've been able to find.
It's odd there is no information I can find on them since since they're clearly factory installed.
Update:Those 4 holes are to mount your clutch and brake pedals should you wish to convert to right hand drive. They are not shown in Teri Ann's photo as her car was a later car. The other hole is some of the same RHD.
Charley