[700rpm]

Hard to tell where your leaks are coming from in the photos. Did you use a sealant on the gaskets? Did you check your pan for straight and smooth face to the block? Was the block clean and smooth where it meets the pan?
You don’t have to remove the manifolds unless you want easy access to the valve chamber, which is separate from leaking issues. Removing the carb will give you a little more wiggle room.

Also hard to tell if you have the brass washers under the bolts that hold the return pipe on. Those are important in preventing leaks from the pipe.