I happen to have a road test of a '69 (Car Life, May, 1969).
Here are some specs...
'69 Mercury Marquis Brougham
Wheelbase/length--------------- 124"/224"
Width--------------------------- 80"
List price------------------------ $3,973
Price as tested------------------ $5,731
Luggage space------------------ 20-cu-ft
Fuel tank capacity--------------- 25 gals
Engine-------------------------- 429-4 bbl
Compression ratio--------------- 10.0:1
Transmission-------------------- 3-speed auto
Curb weight--------------------- 5,035 lbs
Rear axle ratio------------------- 2.80:1
0-30 mph------------------------ 3.5 secs
0-60 mph------------------------ 8.2 secs
0-80 mph------------------------ 13.1 secs
0-100 mph----------------------- 23.6
1/4 mile-------------------------- 16.3 secs @ 88.4 mph
Passing: 30-70 mph--------------- 6.7 secs
Top speed, observed-------------- 114 mph @ 4,000 rpm
Fuel mileage, test conditions------- 10.1 mpg
--- normal conditions-------------- 11-13 mpg
That is very good acceleration considering it's very heavy weight and highway gears.