If it were towed to my shop, and wound up in my bay, with those results...

I'd be pulling valve covers and checking timing chain, timing chain guides, and camshaft timing. Once we established that those things were bad (the guides and camshaft timing, the chain you just replace due to age and the stresses of jumping time), I'd recommend looking for any valvetrain damage on the affected side, and if there was any, recommend removing the head to see what the pistons look like.

I've never had to go that route, as on all the ones we've seen had no valve train damage, but it's the next step if damage is suspected. If you do go that route, it is strongly recommended to pull both heads and plan on doing a valve job on them while they're off.

Once this was all done, my service advisor would put together an estimate to replace the timing chain, guides, and anything else you might need that would be related/in the area. And there's always something else. Usually lots of other things. Little things, and medium things, but they all add up to a couple of extra thousand dollars, so it makes a difference in your final decision on whether to fix things, replace the engine, or just never return our calls and abandon your car on our lot.

That's where I'd start. Oh, and for god's sake, stop turning the thing over (especially with the starter or letting it try to run, if you must turn it, do it by hand). If it still turns, begin repairs now. Once it finishes breaking and locks up, things only get worse.

MV