"I am looking at buying a new contender rifle barrel for my G2 contender and I believe it is an 18" tapered with open sights barrel.  As the opening question suggests:  Will this type of barrel arrangement fit the regular forearm piece ok?"
 
The factory G2 forearm is for a full bull.  Also, unless this is a factory 21" bbl that's been cut down or a T/C Custom Shop bbl, the dovetail spacing might not line up correctly.  Do you know who made the bbl in question?