1973-1991 Dual fuel tank systems theory of operation

[SunSoaked]

I'm converting my 85 to 87 for my efi. Purchased D/S (Main) tank and sending unit. It appears the P/S sending unit remains impossible to find. I read in the description on one of the sites that the difference was which way the outlet hose barbs are pointing and that may be why they are not interchangeable?

So they question becomes, if the hose barbs are made (whatever means) to point inward (away from the frame) would it work on the P/S? I have no problem with fabrication skills.