Im looking for a replacement head for my gen2 3sge.

Are you aware that there are two different types of Gen 2 3SGE heads.
One has mounting holes for a spring type tensioner, and the other has mounting holes for the hydraulic type tensioner.
 
Each head uses a different tensioner idler pulley, top timing cover and it's rear mounting plate that sits behind the timing gears.
 
 
 

Are they interchangeable?

They would probably be interchangeable, but it would be much better to get the correct replacement head to start with because as well as the new tensioner and the stuff I already mentioned, Toyota  also fitted the larger turbo oil pump and oil squirters under the pistons on these Gen 2 3SGE motors. 
 
What type of tensioner are you using now?
If your motor is still in the car you can check with a mirror to check the lower bolt holes in the top timing cover you have.
That will tell you what type of tensioner/head you have. 
In the pic below:
At the top you can see an OEM cover that goes with the spring type tensioner
At the bottom is an OEM cover that suits a hydraulic tensioner. 

 
 
 
 
 

i have the spring type tensioner.
thanks alot for your help!