How many hours should it take a shop to remove, install, and adjust the engine in a Cherokee 180 with a fixed pitch prop?
This would include the baffles and any hardware needed to be removed and installed for an engine swap.
I once changed an engine in the bush when I was bush flying, helping the air service's mechanic. It was a C-180 on floats (I had been forced down in it after the engine developed a loose cylinder from failed hold-down studs).
There was a rigid dock for us to work with at the remote lake we were at, and we used a bipod made of pine poles with a come-along to lift the engine and set it down on the dock (with the noses of the floats against the dock).
It took about 6-7 hours to have the engine and prop removed and ready to be loaded on the company Beaver when it showed up around 5 pm (loading it was the really entertaining part).
We went back in two weeks later with an overhauled engine and installed it, 2 mechanics and myself, and I flew it out that late afternoon around dinnertime.
So for a Cherokee sitting in a hangar with a lift handy, one mechanic with an assistant, about 4-6 hours to remove the engine, and about 6-8 hours to install it. Certainly no more than two days at most.
That's like a 2-4 day effort or more, depending on how many hands are helping, and what the condition of the removed items are. I saw a Cessna 172 get its engine replaced after an overhaul, these are all the things I remember being touched, and it was more than 4 days due to waiting for some parts to come in.
A lot of things are safetywired too, so that has to be all addressed as they go back on. Then securing all the wiring & hoses & tubing. My AP/IA won't let things be tiewrapped to the engine mount, ADEL clamps protect the engine mount and provide attachment points.
And I'm probably missing some things too. Then there's documenting it all.