Yes, easlily with good porting and the right cam. The shortblock would also benefit (not required to hit 400 but it makes it a bunch easier on all things) from a lighter bobweight via aftermarket pistons, pins and rods.

When you think about it, 400 hp is only 50 horsepower from each 44-ish cube cylinder.

360's do get there a little eaiser. (less RPM)