I have both a 400-4spd Tenth Aniv and a '80 Turbo Pace and I love them both.
A stock configured '79 400 (made in '78) runs decent and will really wake up with
some changes, but then it floats away from what it was.
Same exact thing for a '80 Turbo Pace car...
As far as rarity, the 4spd TATA comes in at 1,817 units.
The '80 Turbo Pace car around 5700 units.
More rare is usually more worth. Aside from that, given the
choice you are presented with... I'd take the '80 Turbo Pace.
You should also know that I am the webmaster of the 301
garage, a 301 dedicated site should you select the '80 pace
and need any assistance...
Joe R