Kickboxers switching over to boxing is nothing new. several amateur kickboxers have found great success in boxing. Most notably of course is Vitali Klitschko, then you also have guys like Marco Huck, Povetkin, and I think even Manual Charr had a kickboxing background.
I think plenty of current and past k-1 Heavys would make good or decent Kickboxers. Matt Skelton fought in k-1 and made his name there before switching over to boxing. Kyotaro is 5-0 and is rated as the 106 best HW by boxrec. http://boxrec.com/list_bouts.php?hum...4388&cat=boxer
Jerome Le banner flirted with a boxing career on the side. http://boxrec.com/list_bouts.php?hum...9471&cat=boxer
going 6-0 5(KOs)
Of course Alexander Ustinov was a k-1 guy for many years before he switched over to pro-boxing.
In addition to those guys, Mighty Mo, Mark Hunt, Peter Graham and Ray Sefo have also fought in professional bouts a few times.
Badr Hari was planning to make the full time switch to boxing, he even moved to NY and would took the train to Philly so he could train with Naazim Richardson. Then he decided to stay in kickboxing, and then he started to get into serious trouble with the law again.