VLA archive and reduced in a similar manner. The archival data of MG 2308$+$0336 did not have a primary flux calibrator, so we were forced to bootstrap the flux density from the secondary calibrator. As a result, the uncertainty in radio flux is likely high compared to the other sources, about 50%. Given that our primary use of these data is to constrain the radio morphology and the kinetic power, which introduces astrophysical uncertainties of factors of a few, we do not consider this an important limitation of our analysis.

Methodology {#sec:methodology}
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Integrated spectra {#sssec:intspectra}
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We show integrated spectra for each source in Figs. \[fig:intspec\]. These spectra were obtained by summing over all spatial pixels where the signal-to-noise ratio of the \[OIII\]$\lambda$5007 line exceeded 3$\sigma$. We extracted other line fluxes from the same area. Except for H$\alpha$ in some cases, \[OIII\]$\lambda$5007 was typically more extended than other emission lines. Before adding the spectrum in a given spatial pixel, we corrected for the velocity shift in this pixel relative to the nucleus. Our integrated line profiles therefore give a luminosity-weighted measure of the intrinsic line widths of the extended emission-line gas, which is not affected by the resolved velocity 