Are you saying you have a 302 roller motor and then a 289 motor?
If you're asking which block to use, I'd go with the roller motor and the X303, That what my short block is.
If you know the roller block setup with those heads will give you the 10:1, I would not go any higher compression with iron heads.

I did mine to give 9.5 :1 with aluminum heads and I can run regular gas with no problems.