You are right, some are straight and some have a slight taper - usually very slight, less than what you'd have on the average commercial flared tang. Easy enough to cut some off the sides.
You often see these with two screws in the main / wide part of the tang, another thing that is easily done and makes it look "right". Traditionally they are both wood screws , but usually I will use a bolt for one of them and run it down through the trigger plate.