Looks like internal fuse box it goes to. For the engine loom, But there are two different looms and the difference is that plug, so if it does not plug into the internal fuse box then you have the wrong engine loom for your dash loom.
Going back to your question, It will be very difficult to re pin. To start off with the new plug has 14 pins and the old has 13..... Can i ask what's wrong with your old engine loom?