400hp recommendations for an Ole' 07 wrx.

OK so I tore apart the top of the motor to find the secondary air pump was deleted and that I have like Amazon tubing for the inlet and intercooler -__-. Bought the car to build upon got it for the price of like 2400 bucks. 07 wrx with a seibon hood tho! Okay so it's got 225k on her with no rust but I'm pretty sure the old ej255 has seen enough life. Lookin for opinions and options for like say 400hp ? I don't think I really need or want more than that but a fun street/hillclimb car! From what I've gathered, fp blue, supporting mods, and an iag 550 ej257 shortblock? Send the heads out to get refurbished? Would like to jeep it on a budget but with some nice things as well. It's my project car so it'll be sitting. Also, all I did for now was remove the battery. Should I add stabilizer to the tank? She won't be turning on much to move around for a while.