Once you get to the river I agree you should bluff, we don't block his middling PPs which likely fold, and this is one of our worst hands. Turn I am not sure if this hand needs to bluff, it depends on your range construction.

I like the line overall, but we don't want to turn up with too many bluffs. Say we have some flushes, KK, QQ, KQs and AA for value (lets say 22 combos if ~8 flushes, depends which suited hands you 3b).

3/4 size pot bet means we should have about 3 bluffs per 7 vbets.

On spade rivers this is one of the worst hands we can have (maybe A3s can do this with double gutter on turn).

A5s and A3s would give us 6 combos, which is pretty close to optimal (~9), and if you slowplay a bit of your strong value into different lines then it is about right, or if you check back AA no spade. I would like to be able to bluff the river with a spade blocker sometimes, but we possibly don't have any unpaired ones (if we have the 4 AsJo then we probably have the 7 KQo and we have both more vbets and bluffs).