Well after reading up on Trijicon's website and trying to decifer that chart, I still don't have an answer. The need:
An ACOG with the crosshair-type sights for precision shots out to 600m, for a 20" barrel on a carry handle platform w/M855 62gr. ammunition.
The problem:
TA01-made for carry handle but calibrated for 55gr. bullets.
TA01NSN-calibrated for 62gr. bullets, but for 16" barrels with flattop mounting.

I can't seem to find a happy medium here. Is there an ACOG out there for my needs?

After reading through that chart again, it seems I should only be off when I hit out at 600m or further. Doesn't seem to be a big issue then.

JP Enterprises had a custom reticle built for the TA01, calibrated for 75-77gr OTM from a 20" at around 4000' elevation.

-z

I'd go with the TA01 as the closest to what you are looking for. It won't be too bad until out around 600m where the SS109 will not drop as fast as the 55gr. Even then you'll still be able to put them on an E-silhouette.

However, neither one will be too much of a problem. Under 300m, you won't even notice the difference much.

You can take the flat top adopter off a NSN and put it on a carring handle.