Thresh Mid and Thresh JG

I tried Thresh mid and decided to go AP instead of AD, worked surprisingly well even though I had to roam most of the game after pushing wave. It works in low elo ranked very effectively, evidently. http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2303510061/233731454?tab=overview

I decided to try Thresh jg as a result of my success with Thresh mid in a normal game instead of ranked this time to see if it was remotely viable. http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2304500073/233731454?tab=overview

Any tips on itemization routes for Thresh jg? So far my go-to build is Nashors Tooth, Rylai, Frozen Mallet, mobility boots, zhonya, and jg item (runic echoes or cinderhulk).