Adding fuel injection

I'd like to add fuel injection to my Avanti.   Has anyone installed the pump in the gas tank?   Looks to be a problem due to stand up position of the tank.

I have Edelbrock EFI on my Avanti...no fuel pump was needed inside the tank...a supplied in-line electric fuel pump was installed along the inner frame rail by the gas tank.  

If you do decide to add EFI, make sure you change all your non-metal fuel lines to the proper pressure rated hose.  Standard fuel hose isn't pressure rated.

What Gunslinger said.

I utilized a Walbro inline fuel injection pump. With rubber  isolation of the pump mounting, as well as the filter and regulator, with no hard lines plumbed directly to them, it is extremely quiet. Also easier to change should it become necessary.

I have installed inline pumps in tanks before, and this method is much easier and is quite satisfactory when done this way. Don't ignore the isolation in mounting or isolation of hard line from the noise generator.

While we are on the topic of EFI for SBC's, I'd like to suggest that you use one that also manages the timing either by crank trigger or appropriate distributor. I have a Holley unit on my 83 but it's now an older unit. I'm very happy with the results. Mine uses the 90's type small cap OEM dissy.

The Edelbrock EFI on my car is a previous generation compared to their current offerings but it works great.  It uses a dedicated Mallory distributor designed for the Edelbrock EFI.  Mallory was bought by MSD so that distributor may be discontinued now.  

The only drawback I've found is that the EFI requires a minimum of 10.5 volts to operate properly.  When the alternator went bad let's just say the car ran funny until it was fixed.

Forward,  I had an MSD EFI unit installed on my 76 with the 400 SBC in September 2017.  MSD has a kit that includes the fuel pump (inline), hose, TBI unit, also added a new MSD distributor and spark box. Didn't really put enough miles on it before putting it away for the winter, but it certainly does start a lot easier. The inline pump does make some noise, but I haven't been in an Avanti converted to EFI with an in tank pump to compare it with.  Install was very neat and hard to tell the difference except for the added computer and spark box.