I have built many small block MoPar engines over the years and have never ever used a gasket on the oil pump. Also, I have never seen one that came with a gasket but I have always used Melling pumps. Downside: The gasket can crush at the edges where the attaching bolts are causing the pump attaching flange to become warped with the possibility that the gasket could blow out at the center. Remember that there is only pressure (up to 75 psi) at the attaching point. As a precaution you might check to be sure that your pump is not a Chinese knock off. If concerned about a leak just use some anerobic sealing compound as used on engines with a main bearing girdle. A good parts store will have the stuff.

 

Thanks for that and I appreciate your insight.
The pump is definitely a Melling - no question. I also rotated the pump with a tool, which tells me only that it's not obstructed.

Want to thank the others here as well who have contributed - it has all been a big help.

I'll follow up on my build thread when I go to do the job.