I have never did the milk soak. Sounds like it wasn't washed out good. You have to have wash out the chambers and use a finger to push clots out. We put in a bowl and put a good layer of ice on it. Then sprinkle it with salt and fill with water until heart is covered. Sit in fridge until cooking that day or next couple of days.Well, I tried it awhile back while still fresh. Pretty much followed your recipe ^^^^^ and used bacon grease to fry in.
Tried it rare, medium rare, medium and finally well done with different cuts.
I just did not like the texture of the meat nor the the flavor. It had a real bloody taste even though I'd marinated the cuts in milk overnight. The milk was really red colored so thought I'd got it all. I'll have to pass in the future I think.