Sti engine swap

Hey later down the line I was thinking about doing an engine swap in a 05 RS. If I do so Ill bore, stroke, pistons, valves, cams, everything especially a turbo. Is there a specific place where I can find a used STI Engine.
Also, is the STI block the same block as the 2.5 RS block?

basically....no they arent the same block. i dont know the exact specifics.