There is a stack of material about Wallace on the web - you can spend hours going through it:
http://www.waichung.demon.co.uk/william
Very good, well reasoned and complete - favours Ellerslie Ayrshire
http://www.jimcorbett.freeserve.co.uk/page15.html
Favours Ellerslie near Crosshouse
etc etc
Before we get too excited I note that some of the sites favour Elderslie near Paisley.
Also note the reasonings behind the favouring of Ellerslie near Crosshouse/Kilmarnock they make a lot more sense than so and so's reasoning in the 1800's which seems basically that the Paisley Elderslie is near Auchenbothie and easily found on the map. The Kilmarnock site is much harder to find.