I happen to have a 1G one here right now and my stock GVR4 one in the shed. Although I haven't compared them side by side I would imagine that if you trim down the bracket that the pump attaches to you could probably make it work. The only issue I can think of might be that since the gauge float is "thinking" the tank is deeper than it really is you might get a reading of more than empty when the tank approaches empty. Why are you looking to run a DSM one? Did the fuel line snap off of your GVR4 one? If it did there is a really easy way to fix it.
John