Congratulations on the inheritance. It sounds like you have an inexpensive block plane that could have by any one of many manufacturers . If the blade is steel forge welded on iron, as you stated. I suspect that it is an earlier piece that has been repurposed for this plane. Is the blade tapered? That would also indicate a high likelihood that it is not original. I would guess that a previous owner found the original blade to be unacceptable and simply replaced it with something they had handy.
Have fun with it all and thank your ancestors.