The only engines that could not be turned around and run nose forward both directions were Steam Mountain trams.
The water jacket had to be built level for the % of grade. Then you always wanted the water around the fire box for the maxiumn amount of time.
Now if you are using STEAM helpers. You would aline the engines so that the fire box would be on the lower side during the maxumn work load. As stated before the crew of the helpers do not have to watch the rails ahead. They listen to whisle signals.
Now for Diesels (YAK)
Diesels Run equally well in both direction. The old covered wagons units did not vave any visability to the rear.
Geeps were designed to give this back. Some railroads and Engineers like running long hood forward for protection of the engineer in a crash. But the need for visability made that short lived.
GG-1s were a great motor unit. Problem the motorman could not communicate with or see his second on the other side. The motorman could not see anything with in a quarter mile on the other side. Going around a left curve was done by prayer.
Those Motor units could get a train up to 100mph in about 1 minute.