yeah definitely bet it bigger - OOP i would go for like $1.10 even.
otf, i'd go for like $1.40. if he has a FD he will call $1.10, and he will probably call $1.75. so just charge him like crazy. ott i think $2 should be fine maybe even $2.40 or something then easy value ship otr
actually you absolutely have to get stacks in here! you shouldn't be thinking about how strong it looks, but more how can you take his stack. otherwise you are reaaally missing out on so much value. it's clear he is quite strong here. he can EASILY have Ax, in which case i think you can even overbet ship the river sometimes and he will still call you.