My 70 probably ran a 14.5 or so last year, never timed it. had a 355 with 2.02 heads, performer RPM cam and intake, edelbrock 750, 3.73 posi etc.
My new 71 has a freshly rebuilt (nasty old used pistons out of an old 6 laying in someones back yard, and a head gasket) straight six, I am guessing it'll run anywhere between 22-24 if I dropped it out of a plane...