Not to ruffle any feathers, but how is this even a comparison? I am sure the 904 has it's place in history, but it looks too similar to many other bodies you would drop onto a bug chassis. Sorry, just my opinion. Frans version did look good, but there is a reason I am on a SLC forum (and owner) and not a 904 forum.
Usually when people get so concerned with weight, I ask if they are a good enough driver to relate that into consistent lap times, and are they at or near 7% body fat. Power to weight ratio is very easy to change on the SLC since the chassis is so robust, it can handle it. I plan to tune for 600rwhp on level one, and 1000hp on "ludacris speed" level. At 1000 flywheel, that is 2.7lbs (fully optioned street car) per hp. Do the math on nearly any other hypercar out there, and this is still without full cf body and cf monocoque chassis, or the additional $800,000.
If not racing for money, I would not be so concerned with bench racing weights, and be more concerned about a car that can still wipe the floor with almost any supercar out there. AND, have the supercar looks to go with it.