Tom your car is running exactly the way all the magazine road tests say it should run. Some people think the factories supply the Magazines with "Ringers" just so they get better test results (that occured a lot in the 60's) but I don't think it's a problem now. Because I've been able to match or better the 1/4 mile times documented by the magazines in most all the new cars I've had on the track.
Now for some more good news, All Drag Strips aren't created equal. I assume you made your runs at Quaker City, and one of the things I discovered was I usually turned my slowest times at Q City.
The summer of 71 usually found Sandman50 and I at Q.C. on Friday night, and Dragway 42 on Saturday night. His Mach I and my AMX were both automatics and very consistant runners, and we almost always turned better times at 42.
I saved the best news for last. The best time I've ever ran with my AMX was at Thompson Drag Raceway, and that track should be just about as local for you as Quaker. Before you make any mods, why not try Thompson and see if you do any better?
I am curious, how do most SRT jockeys drive their cars on the strip? Do you use the slap stick feature and shift it manually, or do you simply put it into 1st. and leave it there and let the Tranny's computer do all the work? Sort of a point & shoot method.