Yes Sir the old V-8 OMC engines required a 1/2" fuel line.
Back in 1986 or so one of the local OMC dealers here in Gibsonton put two of these monsters on the back of a 29' Aquasport, made a few magazines as an alternative to I/Os. Did NOT last long, I asked them why they took them off and they told me the boat did not a big enough gas tank to feed them.