I have pieced in drywall myself to blend with existing drywall and if done properly the joint is invisible. It's a pretty common practise. So, yeah it can be done. The issue is how bad is your original ceiling? And since it's probably plaster, how are you going to address it? Will you have wet plaster repair done, or are you planning to cover it with drywall too? That's going to make a major difference in cost and time and frankly if I were having ceiling work done, I'd want it done before the walls.

When I bought my 1874 house the ceilings had all been painted with a paint that had peeled, badly. I tried scraping, but it proved to be an impossible job, so I put in all new drywall ceilings right over the old plaster, which was in good shape, by the way. However, one room had a lot of missing plaster, but I just drywalled over the gaps with no problems. I should add I am a retired contractor and had done ceilings before. It all worked out well, done some 20 years ago. Good luck with your project

First, yes, drywall can be done by amateurs. Not rocket science, just dusty.

I'm a fresh slate kind of a person - I can't stand the thought of drywall over plaster, hate to give up the inch and a half on the size of the room, think it's silly to put that much weight on the bones of the house, and hate the whole issue of having to reset the mouldings.

So my instinct, if faced with your house, would be to remove the dropped ceilings, and remove it all, then re-drywall properly, both walls and ceilings.

In our house we took everything back to the studs - that was crumbling plaster, panelling over plaster, dropped ceilings, and a little bit of drywall over plaster - and replaced with drywall. I'm a bit sorry to have lost all the plaster, but it wasn't adhering to the lath much anyway.

But here's the thing: we wanted to open the walls anyway to run wires and pipes. Maybe that doesn't suit your overall project plan.

Also, unfortunately in some places the drywall ends up being slightly thicker or thinner than the door or window frames, so let's not pretend that installing the moulding will be a piece of cake. You may have already done the work in the walls or not be planning any, so maybe you don't really want the walls open... and maybe the moulding is mostly done. Maybe you're better off with the existing drywall where you have it. If so, wait with all the drywall work until you've wrecked the ceilings, then have it all drywalled and mudded at once. (Dusty. Clean up once).

KarinL

It is not hard to build up layers of drywall to match plaster thickness.

Plaster is usually right around 3/4 inch thick, and two layers of 3/8 drywall gets you there.

If the plaster is on wood lath you may find the stud faces to be unsurfaced wood, and not flat enough to hold drywall directly.

Rip some 2x4s in half to make ~2x2, then fasten these to the edge of the existing studs with screws (no nails, too much chance of piaster damage from driving them in) so the face ends up were it is needed for the drywall.

If you need to skim anyway, make the drywall flush with the plaster face.

This skim coat will cover nicely and make the wall look uniform.

Sistering to the sides of the old studs goes much faster than trying to shim the faces even.

No way would I pay $2500. to have a room still look like a remuddle job. I dare you to pull it all out and start from scratch. You and your handyman need to see what you are really dealing with anyway.

I'm certain the room would look so much better with trim that stuck out like it should and a ceiling that is the original height.

$2500 is a lot of money to pay for another remuddle.

If you're going the smash-up route, be aware that all the plaster and paint hitting the air is loaded up with lead to be sure and perhaps asbestos. Not to mention a century of human scaling and what-all that's been accumulating there.