The entire point of the "raised ports" is to give a straighter angle to the flow.
In the case of the exhaust ports, the first direction the exhaust tube should be is up.
It is true that flow numbers on the ports are more accurate if measured with stub tubes with a minimal radius but that is because most cars won't permit that. Strait up is the ultimate.
The stock headers do not follow the shape that enhances the exhaust flow. They are rather restrictive but with the stock iron heads being worse, that doesn't matter significantly.
To use the high port exhausts in the Pantera, the first angle should be up, If not, you are just wasting their potential. 180° are your best solution to making them work as intended.
The raised exhaust ports are worth about 30-35hp all on their own BUT the better header configuration alone is worth a bunch more. Good 180's "sing". The tune they sing is amazing and completely hypnotic.