I'd say it weighs around 50 lbs. he needed the weight up front, as almost all replicas do unless you have a Mercedes. this took the place of some lead. The engine is built on an aluminum "C" channel so one can bolt to some braces incorporated into the engine mounts so it sits over the Ranger/Gypsy/Ford or whatever you're using.
I have plans and photos I used, but can't remember the details all these years later. I also don't remember where I got the copper from, I imagine from photos of museum ones. I sure I didn't make it up.
EVEN if they WERE incorrect, (which they are not...) standing atop a WWI replica, at 6-8' from the ground, with some cowling... I'm pretty sure that it would convince 99.9999999999999999999999999999999% of viewers.
Like costumers, set designers, prop masters, and composers etc., involved with movies and TV, it need only be evocative. The viewer will take it for what it represents and the cognoscenti will understand it for what it is.
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"I wonder, is it modern art or indigestion?"
--- Orville Wright