If you have 10"hg in D than the 6.5 should be fine.
You can figure out the pump cam by looking at the drivers side of the carb, just behind the throttle linkage bracket on the primary butterfly. There should be a small plastic cam that is held into position with one screw that is on that same throttle linkage bracket. You might be able to see the color better by standing in front of the engine and looking just to the left of the throttle bracket. It could be pink which seems to be a standard pump cam color.
If you are going to buy parts, it might be cheaper to start with the pump cam kit from Holley. It comes with 6-8 different colors of pump cams and they are very simple to swap in and test the 3rd gear bog issue. I think once you have that tuned better than maybe purchase the secondary metering plate (no need for the pv on the sec side) and you can figure about 6-10 jet sizes larger on the sec side than what you have in the primary side if you need to order a couple of jets to test with.
Start with one change at a time and the pump cams should be under $20. Once you know what color you currently have, then we can help you with a guess on the next one to test.
You can use the attached chart to help select a pump cam. The pink cam (for reference) is the "slowest" cam for delivering fuel. You can see this by referencing the chart and looking at the left hand side at the Throttle Degrees versus the number under the pink cam. The numbers under the cam colors are easier to read if you just use them as a "number" (so many cc's of fuel). If you look at the 10 degree number of the pink cam and the orange cam (.050 sersus .022), you will see a big difference of how much fuel each cam will activate at 10 degrees of throttle movement. This chart will help you make a guess at your cam change as long as you know your current cam color and you know that your current cam is setup correctly with the linkage. You want the cam to activate fuel as soon as the throttle moves. You have to readjust the cam pump arm after each cam swap. All you have to do is shorten the pump arm bolt (clockwise on the bolt), then swap cams, then readjust the pump arm bolt so that you get a squirt as soon as the throttle is moved. You may have to make your final adjustmet when the engine is running. If your car is bogging just off idle, then pick a cam with more fuel delivery at 10 or 20 degrees or so. If you need more fuel at 40 or 50 degrees of throttle, then reference the chart to pick the next cam.