it's not exactly dead bug style, i carved the islands with a knife, drilled many holes and did via stitching, literally, with thin silvered wire. In addition to vias, there is also copper tape running around the perimeter of the board connecting top and bottom ground.
The helical filters are on the opposite side. The single shield plate is there to keep the amplified 500-MHz signal from coupling onto the input of the final amplifier. Ideally, each stage should be confined into its own shielded compartment.
The doubler xfrm uses a binocular ferrite and only a single loop of braided copper wire (3 interwoven enameled wires). I am not sure how symmetric this arrangement really is and how well it suppresses the fundamental. There are small attenuation pads here and there for better matching (helical filter response) and amplifier stability.
Because I only found 515MHz triple helical filters, I had to tweak them down somewhat using the tracking gen of the specan.
I would still love to see some photos of your dead bug prototype 1GHz source. Don't worry if it looks messy.