Which camera body is best introduction for beginner amateur astrophotographer? I currently own an old 1980s Celestron eight inch orange tube schmidt cassegrain telescope with tripod. I am seriously looking to dive into some astrophotography. 

I also own an olympus pen epl3 camera. It's great for photos during my hikes, but not quite as versatile as an DSLR. Unfortunately, I know of no software out there which can tether this camera to my laptop. I don't have any great ideas on remotely controlling this camera to avoid shaking my telescope.
I'm thinking of getting a DSLR at some point anyway.

Is there a camera body that anyone would recommend for me?
When I first started out, I used my Olympus pen e-pl1, so you're doing great with the e-pl3. It takes higher resolution photos (330 vs 300 dpi) than my wife's Nikon D5300, so your camera should work just fine. I still whip this one out every now and again just because of its simplicity. 

The one on the right is the adapter that I use regularly. I mounts up easily to each of my telescopes. Works great and has held up nicely the last (almost) decade.



To avoid the shake, set as long of a timer as you can! I'm not sure if the newer pen cameras have the option for the tethered remote, but mine definitely does not. 

As for the software, I wrote some python codes that I use for image processing, and DS9 is the interface that I use regularly, however good old photoshop (pre-everythingisstupidandcloudbased) really works wonders if you're on a budget and have or "find" a copy laying about.

p.s. the adapter is from telescopeadapters.com