155 mph is flying. 149 must have been downhill, 2.94 gears, skinny tires, recurved distributor, etc. I would like to see a restored, blueprinted 440 Polara do that on a test track. Heck what was the top speed of a B body hemi car in 69?
150 give or take, but they had way worse aerodynamics than the fuselage C-bodies. Chrysler did admittedly tune up the cars they sold to CHP anyways. Cop cars weren't all the same as "civilian" 440 Polaras off the showroom floor.