I took the electronic ROM dump of Mattel Jacks and compared the bits to the picture of the ROM array and figured out the mapping. Then I used that mapping to create a ROM dump from the picture of the Plus One ROM array: www.seanriddle.com/cop410l.html
Since Plus One's COP410L was in an 8-pin DIP, I'm not sure which pins were used for which signals, but hopefully that can be determined fairly easily once it is emulated.