It is definately a Protoge head, and it is going back.
The casting number for the Protoge head is BP05-9-1, and after much research I found the casting number for the Miata is BP05-6-1.
Here is a rundown of the problems.
1. There is no hole for the lower bolt of the coil pack
2. There are two mounting tabs right where the coil packs go
3. The coolant fitting on the rear of the intake side for the factory oil cooler is different (looks like it has connections for heater core and oil cooler)
4. The cams are definately different according to some quick measurements with a micrometer.