John:
Dunno about #8, but #6 usually throws a good cylinder-bore pattern from a nitro paradox.
The 1910-12 Holland & Holland catalogue used to be available through a resource page somewhere on these forums.
There are diagrams of the patterns shot during the trials included there.

Nah.... just looked. Only for the 16-bore, and that looks contrived.
Maybe its in Greener's tome?

Hmm. Found a table of right & left barrel pattern data in the "Col. Fosbery and the Paradox Gun" article that accompanied the 1973 reprint of the H&H catalogue.
That will have to do!

Number of #6 pellets in 30-inch circle at 40 yds
right: 206 left: 194
right: 179 left: 209
right: 220 left: 170
This was with the BP loads, not nitro.
Patterns were described as very even, and better than cylinder.

The article further describes the following at 50 yards:
right: 130 left: 126
as being equal to a first-rate cylinder at 40 yds.

...and at 60 yards:
right: 113 left: 117
to equal a moderate cylinder pattern at 40 yds.

Seems fine to me!

Ha! Yet another edit.
Just found the Paradox shot patterns in the 1900 H&H Catalogue, page 26.
They look contrived too, though...