To sort the desired nucleus, select HEAVYION in USRYIELD and add an AUXSCORE card with the respective A and Z, to be associated to the USRYIELD detector.
Select the second sigma option in the USRYIELD Kind, which allows you to set the proper material (COPPER) in the nearby Mat menu (this is essential for cross section - and LET - calculation).
[Note that the polar angle (by definition of spherical coordinates) cannot exceed pi].
In order to get 7Li reactions at the input energy (and not at various decreasing energies, which makes the cross section scoring pointless), redefine the COPPER material by selecting AIR as alternate material for ionisation processes in the MATERIAL card:
MATERIAL 29 8.96 AIR COPPER
(as seen in the FLUKA view of Flair).
To the same purpose, you may want to keep the target thin (to avoid polluting secondary interactions) and bias the HEAVYION inelastic scattering length in COPPER by the LAM-BIAS card (INEPRI, i.e. for primary 7Li ions only).
Finally, the total response that you will read in the USRYIELD sum.lis file, will still need to be properly normalized, prior to becoming the integral cross section value in mb.
First, you need to multiply by the USRYIELD second variable interval (I suggest to choose Particle Charge and set 30.5 and 31.5 as limits, which intercepts Ga and requires no multiplication, being an unit interval).
Then, you need to divide by the 7Li reaction probability, since USRYIELD results are given per incident 7Li ion, and not interacting 7Li ion. This is the Number of stars generated by HEAVYION, which is printed towards the end of the standard output file and should be very close to 100%, as a proof that secondary interactions did not pollute the result.