Two things.
1) Yes. I'd re-gasket and flush/replace all the fluids.
2) Where did you get an L26 that cheap? I need a motor. LOL
Dont touch the headgaskets.
Just do the LIM and UIM, you will have to swap your LIM and UIM over to that motor anyway.
If you got the 2007 L26 with 39K on it it would not need any maintenance so its cheaper then the other L26 with 103K.