428,
I agree with patrick about the wisdom of a Canton RR pan (or equal). I had the same 6 qt. truck pan you describe on my old 428. While making laps at Bridge Hampton, I watched the
oil pressure sink to 30 psi at 5500 going under the bridge and ceased to have fun that day. The Canton went on the following week. Yes, I know you're using your car in a mild way but it's just really good insurance to never worry about, as well as improve ground clearance as mentioned. No one will know you "incorrect" pan secret unless you turn your car up-side-down. Please don't, I love beautiful ERA "street" cars.
I have the same dipstick as SSSammy, which worked perfectly in the 428 and now the Side Oiler. As a further display of anality, I hooked a simple spring from the finger loop to the header tab and stopped the
oil weeping the ancient dipstick displayed. Put a tight fitting o-ring around the tube ferrule too.
My 2 cents.