My 1982 Direct Connection "B-RB Engine Racing Manual" shows just the 8.5:1 400 in a 3200# (less driver) Duster with 4.30 gears:

Stock Hyd 12.35 @ 110.27
Street Hemi 12.17 @ 112.60
.484 11.91 @ 115.30
.509 11.82 @ 116.61

but then later on they show the .509 as "baseline" with the same setup but .05 faster and 2 mph slower (11.77 @ 114.80), then:

.528 11.69 @ 115.90
.557 11.55 @ 117.05
.590 11.45 @ 118.00

So it did keep going quicker if not always faster

It would have been interesting if they'd kept going beyond anything "reasonable" for an 8.5:1 smogger right up to the .620 (and even the mushroom .654, which is only 4 deg more advertised duration, 316 vs. 312, but .034 more lift)...