What oil pump to use?

Kent mosby said
As to clearances, this is a new build and we will be using 1/2 groove main bearings. The RPM will be 6800 or so, hopefully. Not sure. I will run it on the run stand and see about the oil pressures throughout the rpm range and if needed, upgrade before final install.

Your plan and answers are raising a few red flags with me.
Not sure the 1/2 grooves are the way to go. Not a long stroke, not living at 6800rpm.
You are not answering the clearances question and setting the pressure "after it's dyno'd" is just totally *** backward. If you are using a stroker kit the clearances need to be measured. We're talking about thousandths of an inch here. .002" clearance is fine with one setup. .003 or over should have more. So it's not a "we'll see". If it's a stroker kit, get the parts, have the block machined (assuming the main bores are also being done) and have everything measured with the right tools. Not plastigage. Only once those are known via empirical means can you really determine what system will be adequate. Also FYI - most kits with lower and medium price points will have clearances that are all over the board.

IMO, a stock pump and pickup will not be enough for the rpm you're suggesting. You need a little wider clearances for it, some internal passage modifications, and a full grooved set of mains for that rpm. I would plan to open the factory pickup passages, including rounding off the sharp bend in the passage above the pickup boss, and enlarging the main feeds from the passenger side lifter galley. I'd spec an HV pump because it will need the volume. BTW - no HV pump I know of comes with a std relief spring. They all have the HP spring in them... A better pan would be some insurance - even if it's just the Hemi style factory unit with a windage tray.

I'm not sure what you have for a head choice. To make power at those rpm levels you've got to be putting some real heads and cam on it too. And those heads and/or cam may have different oiling needs too.