Living with a 2.21....

I am shocked that you can make 19.2mpg USG, at 75mph, with that combo at 130psi.
As to the horsepower, that 268 probably peaks at around 5000, which in first gear will be around 63mph, with the 2.74 low gear,lol.
I like the 3-2 downshift at 60mph tho; right at about 3900 where the teener is swollen with torque.
3.55s are to 2.21s sorta what one more gear in the trans would be.
That is to say, the 3.55s will multiply your first gear torque by 3.55/2.21=plus 61%.
And the A500od will drop the cruise Rs of the 3.55s from 65= 2930 back to to 1730, or 59%.
But 3.91s are a better fit for the A500, dropping the cruize Rs from 65=3220 to 65=2220................. And the new starter gear of 3.91x2.74=10.71 will really wake the teener up,especially off-the-line.

But I just gotta say, if all you are after is a lil more giddy-up off the line, a lot more compression, or a lot earlier ICA, is the answer. Failing that, a looser TC is the way to go.Of course the compression will fatten up the power everywhere.

And I agree that if you are running a PV, your 72/74 jets would normally be considered way too big ,and the stagger way too small.Typically the frt/rr stagger with a well matched PV is 8 sizes.In all likelyhood the PV is coming in too late if at all, and the 72 is in there to compensate.
When I tune, I ballpark the timing with the T-port sync dialed in and the power-timing ballparked in the 32 to 36 range, coming in somewhere in the 2800 to 3400 range,depending on how tight the TC is.
Then I disable the secondaries, and plug the PV. Then stick a too-small MJ in there and go for a ride. I want to cruize on the top of that MJ, so if you cruize at 2200, I want that MJ to hit at least 2200, before leaning out. Jet up as may be required. Then start on the PV
I might consider doing a LeakDown test.
Just to compare; I run 72/78s on a 750DP fueling my 367HO@400 plus hp streeter.
I also agree that the mighty AG is probably not the best intake for your combo.hat's probably another reason for the 72s, or possibly THE reason.