Hubcaps were NOT standard. They were optional. And they remained optional for all Low Pro models. Good luck finding a decent "original set" of caps. I am not aware of any aftermarket units that replicate the OEM caps.
Mower decks were not standard either because the 130 was a GARDEN TRACTOR, not a LAWN TRACTOR. As such, there is no requirement for a deck in order to have a "complete unit." When dealers placed orders, tractors came in as a separate item. Decks were packaged as individual items and so were snow blowers, utility blades and so forth. When a customer sat down at the dealer to buy a CASE Garden Tractor, he started off with a BASIC tractor and then added whatever options and attachments he needed. Some tractors were sold with no deck. Instead, they were fitted out to power the hydraulic rototiller.
A mower deck on a CASE show/parade tractor is a PITA. They barely clear the ground when fully raised. It is common for them to hang-up when loading the tractor on a trailer. No one will criticize you for not having a mower deck. If they do, then they don't know what they are talking about.