Big Block seems to slow

When I was in the Air Force, stationed out in Sacramento, Ca I bought a 69 Charger.
This was in 1980.
I really didn’t know anything about anything, but I did learn to look at the VIN to see what engine was in the car.
This car was an “H”, so a 383.
It had a 4bbl on it...... so I “assumed” it was as appeared.

It was all stock....... and was a bit of a dog.
I tuned it up, and drove it to Sacramento raceway to see what it had.
After a few passes....... it was in the 15.60’s as its best.
That seemed kinda slow to me, so I checked the rear gears........ 3.23’s.
Okay, not terrible.
For some reason I was suspicious of the engine.
I looked on the block where the serial # was supposed to be and nothing was there.
Then I cleaned some greasy stuff off by the distributor housing..... and there it was........”C361”.
I guess the 383 had died, and some bone yard ‘66 361 was installed in its place, and they put the 383 intake & carb on it.

That satisfactorily explained the uninspiring performance to me....... and I started looking for a 440 core to build to replace it.

There’s a ton more easily accessed info now than there was 42 years ago(and I know a tad more than I did then).
Depending on what the goals for the car are........ I wouldn’t necessarily rule out the 361 as quick as I did in 1980.