LOL no,Overeem is not even near HW kickboxing top 10 of all time...
He was just the famous story of the guy who was in the right place at the right time,the years he competed on K-1 HW tournaments(2009,2010) the HW division were pretty falling in terms of elite HW kickboxers(with most of the best kickboxers were old, Retired or dead like Aerts,JLB,Hunt,Andy Hug,Mike Bernardo,Hoost,Sefo,Ignashov,Stefan Leko,Bonjasky,Glaube Feitosa,Francisco Filho,Greco) and maaaany maaany others.
-He never faced really tough opposition aside a weak chin Hari,he defeated and old and very prime passed Aerts,(even very old he was better than most of K-1 HW´s at the time),being the second time he defeated Aerts,he was very tired because he went to war to defeat the monster Semmy Schilt,so the Steroid young guy had an easier work against the "crazy old man"...
-He defeated an broken arm Saki who is too small for him.
-Another small HW he defeated,Tyrone Spong(who gave him some problems)
-defeated Teixeira and Poturak who were medium-good kickboxers for THEIR TIME
-Edwards who were another good kickboxer for their time.
So as showed before he was just lucky on entered in the tournament and faced an very much smaller opposition than K-1 HW tournament used to be in early 2000s and years behind.
Guys who were much better ranked than Overeem in HW best kickboxers of all time(in terms of better wins,more decorated career,most significance on the sport) :
-Aerts
-Hoost
-Bonjasky
-Schilt
-Hug
-Sefo
-Hunt
-JLB
-Cro Cop
-Ignashov
-Mike Bernardo
-Leko
-Branco Cikatic
-Francisco Filho
-Greco
-Matt Skelton
-Saki
-Hari
-Glaube Feitosa
-Verhoeven
-Slowinski
-Ghita
-Samedov
-Londt
-Musashi(even with the gift decisions he received he still having a much more legit than Overeem,and he was a good fighter aside that)
-Stan the man............
believe there are more guys in this list,but i already remembered a lot of guys who would deserve to be higher ranked than Overeem in a best HW kickboxers ranking,as i said before,he was just the lucky guy,who would be an average joe in k-1 HW prime days..
Im not saying he was a bad kickboxers,because he was good,but he never faced the amount of guys who could kick his ass in their prime.