There's no getting around the labor since the transmission has to come off to replace anything between the engine and transmission.
I got my 81 SD (sold) after the transmission locked up and shredded the flexible 3-arm part of the flywheel/flex plate. I can probably do it in less than 8 hours but I can see where that's the standard book time for the job.
You can do it yourself with basic tools. You can lower and raise the transmission with a floor jack. You don't have to lift the car very high if you're not pulling the transmission out from under the car.
The flywheel/flex plate on this car has 3 peices and I don't know all their technical names. The ring gear has the teeth that the starter engages. It's just an annulus (sp?) that fits over the main flywheel. There's also a flexible plate that has 3 arms that the torque converter bolts to.
I think you have to replace the flywheel to crank bolts when you remove the flywheel. At the very least use Loktite.