After removing the rust, I leaded all the holes.
Leading is actually pretty easy once you get the
hang of it. Unfortunately, it's just not the kind
of thing you stop in the middle of to take
pictures.
The real trick is getting a large area to the right temperature, without overdoing it, so that you can properly tin the area. I used a propane torch, but an acetylene torch would have made it much easier. After tinning, you heat bits of lead until they are soft, but not runny. You just spread the lead around like frosting a cake.
After leading the holes, a retreated everything with baking soda and water, then flushed the whole interior with a metal-prep rinse (zinc phosphate, I believe). I rinsed it one more time with acetone, and then covered the whole interior with POR-15.
The real trick is getting a large area to the right temperature, without overdoing it, so that you can properly tin the area. I used a propane torch, but an acetylene torch would have made it much easier. After tinning, you heat bits of lead until they are soft, but not runny. You just spread the lead around like frosting a cake.
After leading the holes, a retreated everything with baking soda and water, then flushed the whole interior with a metal-prep rinse (zinc phosphate, I believe). I rinsed it one more time with acetone, and then covered the whole interior with POR-15.
The next step is to cover the leaded areas with a plastic filler. Meanwhile, here are some before and after photos.