Hope you are not trying to do this with todays pump grade gasoline with an original engine.
Those YS code engines were sittin' @ around 10.0 : 1 when new.
Todays low octane pump gas will pound the bearings out of it even with a conservative( extremely retarded) tune up. 96 to 100 octane was required for those engines.
If you are driving this car everyday the tuneup may already be way off to compensate for the low octane gasoline.
A compression test & leak down test will tell you if you still "have an engine".
@ 90,000 miles on the clock (car is 37 years old . I put 300K on my 1970 350 'Bird before I parked it in 2003. It had 95K on it when I purchased it in 1976 .Are you sure yours hasn't turned in 100K already?)
A 1970 Pontiac 350 2V engine had a CR of about 8.8:1 and they would rattle on 91 octane premium without some serious re/de-tuning
Before doing any racing I would replace the original timing chain and gears.
These are on borrowed time after about 75K miles.
If they let go or jump position the engine will just refuse to run.
The worst thing is when the plastic coated teeth on the cam gear let go they scatter all over in side the crank case which requires pulling the oil pan and cleaning out all the debris.If any of that trash gets by the oil pump pickup screen it can cause the gears in the oil pump to jam which can cause the oil pump drive shaft to shear.Engine keeps running with no oil pressure, for a while.You would be lucky if the roll pin on the distributor gear sheared first, then the engine would just quit.
Stock valve springs can be getting pretty tired at 150K ,I was breaking them at 225K.
Replace the distributor with a new MSD, Accel or Mallory breakerless unit.
Upgrade the coil too.
Is the ram air on the hood functional? If not make it so.
Low retriction air filter element(K&N).
You have improved the exhaust but have done nothing to the intake side.
Increasing air flow on the exhaust side may require richer jetting on the carb.You may find it's laying down on the top end ,too lean.
Put some good unleaded racing gas in it and play with the tune up.
(I suggest frehening up the engine before trying any of this though.)
Go out and do some base line runs.Keep your revs below 5700 rpm.
You will find there is a lot of ET to be gained by improving the 60' times .
This will involve gearing, rear tire diameters & widths , suspension reaction tuning / weight transfer.
8 to 10" wide sticky rear tires.
If you cannot change the rear gear to a 3.73 04 3.90 ratio go with the shortest sidewall tire on a 15" wheel you can find. 24" dia. to 26" max dia. would help out the 3.55 . 22" tall M/T ET drags are available but the weight of the car may preclude the use of them. You would want to consult with M/T first.
I think the 1970 cars had 14" wheels and those are hard to find slicks for.
Play it safe.