if you look at the fuel line exitting the fuel pump you will see the size of line you need to supply the fuel pump. the outlet side currently looks larger than the barbed fitting on the inlet. is that how the pump came or is that something that was put together? usually a pump has a larger inlet size than the outlet size. personally I would use a different style of fitting on the pump inlet because the brass fittings with that flared style connection usually have a smaller through bore size, meaning, if you look at the inside of the fitting the hole in the middle is actually fairly small so the amount of flow through the fitting is reduced. flared fittings are usually made for a tube, like the one on the frame, and the actual connection seal is made in the contact of the flared to the seat on the connecting fitting it is screwed together with. that part is larger than the steel line so the through bore is the same size as the inside bore of the steel line.
you could try an auto transmission shop and aks if they have any adapter fittings for your size of steel line to adapt to a hose. something like this, which is made from a steel line and has the bulb for hose connection
https://www.agscompany.com/products/...to-rubber-hose