In high-gain reactor-relevant fusion plasmas, alpha heating dominates the power balance. As alpha particles thermalize, they transfer kinetic energy to the bulk plasma via collisions. At the MeV collision energies characteristic of alpha thermalization, nuclear elastic scattering cross sections become comparable to or exceed the Coulomb cross section, greatly enhancing the probability of large-angle scattering events. These nuclear interactions can accelerate a fuel ion to several MeV in a single collision, producing distinctive non-Maxwellian fast "knock-on" tails in the kinetic distribution functions that are characteristic of thermonuclear burn. This effect has been experimentally confirmed by the observation of fast neutron spectral tails at the Joint European Torus and at the National Ignition Facility. Here, we present the first kinetic simulations of alpha particle knock-on ion generation for the SPARC tokamak's Primary Reference Discharge, a 12.2 T, 8.7 MA H-mode scenario projected to achieve a scientific gain of ∼ 11, deep in the burning plasma regime. We couple the bounce-averaged Fokker-Planck solver CQL3D with the Monte Carlo reaction integral code DRESS, implementing a thermally broadened alpha source term, large-angle scattering corrections to CQL3D's collision operator for deuterons and tritons, and a synthetic neutron spectrum diagnostic. The knock-on ion tails evolve toward a kinetic steady state after about two alpha slowing-down times (∼ 600 ms) and comprise approximately 0.1% of the total fuel ion population, with the fast-deuterium density slightly exceeding fast-tritium, consistent with nuclear resonance in the α,d cross section below the alpha birth energy. Equivalent Maxwellian fits to the fast-ion distribution functions, assessed with log₁₀-space coefficients of determination R²_log, are adequate for describing knock-on fuel ions (R²_log = 0.64-0.89), but are fundamentally inappropriate for the alpha slowing-down distribution (R²_log ≈ 0). Synthetic neutron emission spectra computed with DRESS predict a steady-state alpha knock-on neutron ratio of 8.8 x 10^-5 and demonstrate that SPARC's magnetic proton recoil neutron spectrometer will be sensitive to the alpha knock-on neutron tail, providing a direct observational diagnostic of alpha confinement and thermalization in a magnetically confined burning plasma.