Disappointed with my engine

Now that i have caught up here is my thoughts.
if your shifting at 6000 rpm as well as going thru the traps(finish line) at 6000 rpm..........anything bigger then a 650 will not make you go any faster(my opinion)
Next. Ask any porter and they will tell you the most impotent part of a port is 1/2 inch above and 1/2 inch below the valve seat. Why did i say this????? if they cut a 1.92 seat from a 1.88 original seat and didn't do anything else........that bigger valve will flow less cfm and will run BAD. Something to think about.

You need to try and not take offence to words on a page......that's all it is. And them words can help you run better and faster.
Zoomies are cool!!! But the cool factor is slowing you down. don't get up set about it. Try it! Prove we are wrong..........

My next Thought, your running a lot of lift, more lift then a un modified head can handle without the the retainer hitting the guide..........do you have enough spring to keep the valve from floating at that lift.
You have a new head so these thought should be in the back of you head for you new head.........

With a 5000 rpm stall, there is no reason for a vac secondary carb! But at this point, is vary minor for your power lose.

I run 4.56:1 gear ratio with a 26" slick. 408 that go's to sleep around 5800-6000 and still go thru the traps around 6500 rpm. in a 3800 pound car. So yours should be doing much better then 6000 rpm........Which you already know.:D