Pre 72 most HP ratings and such were taken at the flywheel. Now this is what I was told and I do believe it. 72 and up HP was measured at the rear wheels through all the accessories so to speak. That is why the pre 72 models always looked good on paper with the HP ratings.
Now you add an auto trans to the mix and you loose 20-25% off the engine rating, then you figure in wheelbase, rear end gears and tire size and put that on the dyno and you will see what the true hp is. Of course a little tweeking and such and you could have a decent runner. How your car is timed, carb jets etc all can give or take away hp if you do not know what you are doing.
Klasse Act, just go for it. These new cars are pocket rockets compare to the old. He may get you off the line due to torque, which you do not have in car due to your engine size and such. Torque launches the car and Hp keeps it going.
But with your short wheelbase and plus the fact that you are going from a rolling start(I would do 25-35 mph) for your car since that should put you close to banging 2nd really fast whereas if he has a 727 auto and has a 3.08 then it still should be in first which would prevent the auto kickdown working. BUT if he shifts manually then that may be another story.
Heck I don't mess with Wrx's, I can get them off the line but once those babies spool up, they're gone
Its embarrasing but like I said you can't beat new technology.