Spraying will produce a nicer finish - especially with the black satin. If you father can help you with the spray (case of beer, invite to a BBQ, etc.), that would be ideal. You'll learn for the next time around and get a nice cab. Take a look at the notes here and the painting guide listed at:
http://www.rgvac.com/restoration.asp?projid=16 There is some great info in both places.
That said, others have had success with high-quality, super tight nap foam rollers. Do a search here for more info.
Note that painting will take some time. I recommend you apply one or two coats of primer *and* sand with 240+ grit afterwards. You want those sides really smooth - like glass. Ideally the primer should cure for several days to a week, depending on your weather or workshop temp and humidity. Once the primer is set, you can then do the satin black. Again, you may do more than one coat, depending on how the first comes out. With a sprayer, you'll probably need to thin the Rust-Oleum with *acetone*.
Finally, after a week or so of letting the satin black dry, consider a coat of clear sealer to protect the paint and your work. I highly recommend the notes on rgvac.com.
John VV