Build questions please help!

I have a phase 1 22t block that I plan to put into my 04 WRX sedan, I am curious if I should use the heads off of my stock ej205 or I could use some 251 heads with Delta 1500 cams that's have been port and polished, I've heard the 251 heads will require modification and some wiring to make them work where as the 205 heads should work fine, also what head gasket should I be using for the 251 heads? There's a ton of info on using the 205s but can't seem to find much on the 251/ 22t hybrid, also I'm curious what injectors I should be getting to support 380-400hp? Thank you!