I think Monte is correct (again). The valve covers are nothing like the 99 Hemi, they look just like the Kaase Ford Hemi (which is not at all like the real original Ford hemi design) with the spark plug locations moved. Morgan's Ford Hemi was just a copy of the 99 Hemi, which was a copy of the Chevy wedge with the spark plugs moved.
I feel if it does not use factory parts, that is with factory part numbers, it is simply aftermarket. Several years back Dodge Pro Stock teams had to come up with another block as the one they were using was the same one used by Chevrolet, even though they were manufactured by an aftermarket company. In today's cookie cutter Pro Stock cars, I suspect even the NHRA would allow all makes to use the same parts, if it was not for sponsors crying foul.
There is nothing stock about Pro Stock.

Danny