I know nothing of your skills or finances but for what it would take to get 400hp out of a 350 you might consider an LS3 engine. It is a 327 that easily bumps the 300hp mark and gets 25mpg. I see on Epay they are selling in the 1k range and a controller harness is 12 hundred. Figure another $500 for motor mount adapters and exhaust by the time O2 sensors and bungs welded in are factored in. For 3k you can have an engine that has bukoo horsepower, idles baby butt smooth, and easily goes to the 250k mark on the odometer. Just one other route to consider.
