I was given a dataset generated in MapInfo. I need to use these files in QGIS, so I imported the .TAB files and saved them as ESRI shapefiles. I then realised the original dataset uses a custom "user defined" CRS. When I change the CRS from this user defined system to WGS84 in QGIS, serious positional errors arise! The shape is also wildly altered.
How can I reproject the data to overcome the positional and shape errors? Is there a way of changing the original MapInfo CRS to WGS84, ensuring the shape and desired positioning will be correct in QGIS?