Which is the head that fit onto the 7A bottom end? which kind of mods I need to do this swap?

don't do it, it's a gigantic pain, you have to rewire the entire car, custom make mounts for the AC, you may loose power steering, and it only give you maybe 20-30 HP at the flywheel, and it's all high end power, no torque. not. not. not worth it, unless you have a few engines laying around. it can be an amazing engine, but it will be out of your car for months, and it will take several thousand dollars to do it right.