Velobase shows that victory 116 chainrings were available as small as 35 tooth (good luck finding one though . The RD should accommodate up to a 28 or possibly a 30 tooth freewheel cog. Probably much easier to rebuild the freewheel as a 7-speed 13-14-16-18-21-24-28 to increase the range. The gearing change from a 24 to 28 tooth chainring is a fairly substantial difference, it just wont have the tight gear spacing that a narrower freewheel provides.