Holley 750 "stumbles" on WOT

Since it needs a kit anyway, my advice is build it. Get all of the adjustments dead on for a good base line and go from there. I wouldn't put different cams, pump shooters or anything in it yet. Build it back STONE STOCK. That way, you have a base line. You said it ran good for a while and then started acting up, so I see no reason to change anything just yet.