I'm assuming this applies to the styled wheels on my Sprint B too. Argent on the outside and semi gloss black on the inside, correct? Or should the inside be a satin black?
Yes. An argent painted wheel in 68 is the same as another based on what I've seen and what we have collected. They didn't have "satin" in the day so you/they only had gloss and semi-gloss to choose from. Not all the designer terms and different products of today so yes - semi-gloss or what ever you can find that reproduces that look.
You might want to create a sample board for long term use as mentioned in a couple of other threads. Take a piece of strap metal, gusset or similar piece of metal, buy a hand full potential spray cans and paint stripes (maybe an inch or two wide) along the length of each color then use it as a guide to which black you want to use on any particular part in the future or to compare to original paint samples to chose the closest match. Black painted parts, for example, in the engine compartment, would not have originally all been the same since they were painted at different locations, with different paint supplier, mixes and conditions so this can help with that also.
Here is a similar test or sample board I used for floor/undercarriage colors