Looking through a bunch of Marti reports and comparing it to what you've provided so far (63A body style) I see so far that when styled steel wheels were ordered they were noted in the Marti report in a number of examples. Unless Kevin has changed by leaving out details (doubt it) then at this moment it suggests to me that your car received steel wheels. Also you didn't mention that your Marti report list any mention of hubcaps (something shown on other non- Mach I examples) which IMHO suggests that your car likely didn't receive a set of full hubcaps but likely the standard "dog dish" hubcaps and because of this painted (to match the car) steel wheels as we have seen on other cars. Since you didn't mention it I assume that this was not a GT car orginially
For the rest of the story/question
..............The field immediately to the right of the tire code is "522WF" would that be the wheel?
522WF
This refers to
"5" tires (4 on the ground and 1 in the trunk)
"2" 2 ply tire
"2" identifies the type of tire (don't know the definition of a 2 verses the other numbers at this time) could identify the supplier
"W" believe this refers to the white wall side wall
"F" find this on some but not all buildsheets in 69. The form did change a number of times during the production year so that might explain why it was not always used.
60ARS ...
If you can read the lines above each they are
"60" Wheel size = 6"
"A" Wheel color
"R" Wheel style
"S" Wheel type
Followed by Wheel code on some versions
Looking at other buildsheets I found the same codes for wheels had been used on base model Mustangs that would not have been equipped with either Magnums or styled steel wheels IMHO All the codes other than the width of the rim also matches even the most standard of the Mustangs with the 5 1/2" wide rims
So we're left with narrow base wheels painted body color or semi-gloss black. And as mentioned above (the no hubcap mention in the Marti report) I think there is a good case to make for body colored wheels originally
Hope this helps