There's so many Ballards out there in the same situation (forend assembly swap) that I really don't think that hurts them much if it all fits well and looks to be the same age. 
A newly fitted barrel and forearm will of course look much newer than the rest, so you may want to also set aside, or sell the buttstock also, as it would look much different.

When Westy (Lee Westergaard) first posted to this thread I emailed him.  He lives in Iowa and yes the rifles were/are Chris, Auggie and Jim Westergaard's rifles.  From what he described at that time (early 2010) there are some real gems in the collection.

I encouraged him to find out everything he could about the rifles since the things that add the greatest value to rifles is the provenance (who owned them, who shot them, etc.).  The .22 he described belonged to Otto Hubaleck.  One of the Stevens he has was the one that his Grandfather C.T. Westergaard won in match prior to WW I (a Stevens-Pope).  The Ballards were various, Schoyen, Peterson, Zischang and others.

He also has a collection of "real" gold Schuetzen medals that C.T. won that apparently were hidden prior to 1934 to keep the Roosevelt administration from grabbing them.

I had encouraged Lee to contact some auction houses and get expert advise from collector's prior to auctioning off any of the rifles.