Confirmed that he is on the southern most island on the south side of the island. A tad bit harder in my opinion then Silithis Sisnta; successfully duoed as a 77 SK with a tier 2 healer merc no sweat and never dropped below 65% health.
Hits fast for the low 200-300's and hit for two times at 1036 on 2850 AC all defensive's maxed for level.

Gubblegrot's Head