ASG should be able to flex tune it with VERSO, but best to still chat with them a bout your options because as Goosey outlined its almost a full fuel system change out for ethanol safe components.
As for intercooler upgrades Process west offer you three options:
PW Verticooler - good design, higher undisturbed airflow through cooler, but at a higher cost then a normal TMIC.
PW Topmount Intercooler - no longer in production for GR WRX but can be found second hand, good upgrade over stock with multiple units shown to be able to handle over 330hp on pump 98.
PW Frontmount Intercooler - offers the best flow and HP support, but most expensive, most likely have to cut various supports and panels to fit and in my opinion not worth the effort unless you will be shooting for +400hp.
There are other kits on EBAY that all say they fit GR WRX's and that outflow Process West but I am yet to see one that fits properly and uses a decent intercooler core. So stick with a trusted brand, especially since you out a lot of money into the current engine.
To get the most out of the new engine a larger turbo and intercooler combo would finish it off nicely
