That mioht work if you have a large enough lead pot to melt that much led. Cold joints will not stay together as the melted lead will not bond good to the cold lead. Also there is more to it than just melting the lead and pouring it into the mold. As you melt the lead the zink will come to the top. You will need a bonding agent, like bullet wax to mix the zink back with the lead before pouring. Will take a heck of a cast iron melting pot and big burner to melt that much lead. If that is an aluminum pan, when the hot lead hits the bottom it is going to go 7 ways from sundown.
I would check with ag salvage yards for some of the smallest weights you can find and build your holder to accommodate them. Be a whole lot less trouble and would work better in the long run. Just my opinion from making several thousand round of bullets in years past as well as lead head for fishing lures. Good luck, Kenny.
I have to second the part about having a big enough pot for melting the lead based on the misadventure of my teenage years.
We used to walk the railroad tracks, collecting the lead from bearings the railroad blew out of the boxes.
My brothers and I got the idea to make lead head spears. Dad who had a lot of foundary experience supervised.
We poured the first one with not trouble melting it in a coffee can, the second we were short on lead, so melted some more and tried to add to the head, it blew up(molten lead everywhere) and my brother to this day has a small scar on his cheek that looks like a cowboy hat.