I would invest in orange head roaches. I just sourced some Ivory head roaches, they are really similar to orange heads.
The reason I like the orange heads is that they are bulkier. So they have a bigger gut for loading. They breed faster and are actually kind of pretty for a roach. Nymphs are a glossy brick red color. Adults are tan with a bright orange head.
If you can find ivory heads they are worth a shot. Most dealers want $3 per roach because they are pretty rare. Roach Crossing had some, I purchased 40/$38 yesterday (shipping included). I should get them next week.
In the future I may be able to provide both orange and ivory heads.