OK, here's some data: first, in TARGET v2 #1, Uncle Sam assembled all the Target heroes together, Target, Chameleon, 2-R, Spacehawk, Bull's-Eye Bill, etc., and told them what they'd be doing for the war effort. In the same ish, the Chameleon guest-starred in the Target story. AFAIK, those were the only TARGET X-overs...but the Twister guest-starred in every other story in the issue of BLUE BOLT where he first appeared.