Most 3.5 items cross over without a problem. A player I have wants to use an item from 3.5 that let's him turn undead as 1 level higher. What would be an appropriate pathfinder version? I am open to all suggestions.
Does he want to use it to turn undead or does he want to adapt it for channel energy?
If he just wants to turn undead let it work at written. If he wants to increase his channeling have it be a special (un)holy symbol that adds +1d6 to channeling.
Often I allow a lot of 3.5 items that were never brought over because of copyright issues.
Some items in particular should be changed up a bit though to make up for a lot of the changes that PF made to magic items. e.g. Monk's Robe instead of a Monk's Belt because belts are typically reserved for stat items.
Just be aware of changes like this when allowing items to be brought over.
Another thing to watch out for is custom items that allow you to tailor which item slots are dedicated to what, which could end up overpowering a character because PF spent a lot of effort in not allowing multiple items with the same effect on multiple slots to prevent that sort of thing. e.g. a Ring of Natural Armor in place of an Amulet because the player wants their neck slot to be open in favor of another magic item.