a 5spd manual 2.6 is probably rarer than a 2.3-16 (probably as rare as a 2.3-16 automatic?)

a (non-Sportline) 2.6 can easily be given a chassis upgrade, although its heavier nose will prevent it from matching the 2.3-16 in handling.

the 2.6 is a sleeper, being devoid of wings and aero aids.

the 2.6 will probably have a lower insurance premium.