Probably the easiest 240 clutch job there is. The trans is a simple deal without the OD. Pull back a bit, spin a bit, and it's on the ground. The cross pin for the shifter may give trouble, but other than that, no problem.
Sachs or Luk clutches are my preference. However as I recall the '78 was a transition year from the coarse spline ( 10) to the fine spline input shaft. Unless the VIN confirms which you have, get the clutch after removal.
Loosen the three nuts at the exhaust flange, and let the engine down onto a piece of wood against the firewall. Don't twist the exhaust down.
Change the trans oil while it's out - use ATF, and Dexron is just fine.....
If the flywheel is not heat checked scuff it with emery cloth or 320 grit wet/dry paper. Replace the rear main seal, but carefully. More than enough folks have introduced a leak when there was not one present previously.
$800.00 is a bit high for a non-OD clutch job. On a hoist, if things go well, it's a one and half hour job. Flat rate is four to five I think.