re: Gas range hood install cost

1)it needs to vent outside...so either through an exterior wall or up to the roof. Depending on your layout, you may not be able to convert....
2)it needs to have sufficient CFM draw to be useful based on the BTU output of your stove. IOW, if you're using a high-heat stove, a low CFM hood won't do you much good.
3)you need to determine if the higher CFM draw is going to require make up air to be pulled into the house (whether you need MUA depends on how tightly your house is sealed, kind of heating/HVAC, and other factors)