Can someone please tell me what engine component this is with the arrow? Probably a stupid question. Thanks

Fuel injection pump?

MPS, decel valve, hose.

Thanks. I am building a six conversion and would like to install the fuel pressure regulator in that location.

Manifold pressure sensor

One of the most important parts of our FI

MPS that's required for fuel injection to work properly. Do a search on here for how to test it and you'll find lots on info.

If your doing a conversion and your mps actually works properly you'll be able to find someone who wants it.

IMO that's not really a great location,its the opposite side to where the fuel supply is,you don't really want fuel hoses going everywhere,less hose is less hassle.
However its your car to do what you like .
I mounted mine on the rear bulkhead,easy to see ,adjust and close to carbs so shorter hoses.
Click to view attachment

Holley LP regulator ,Mister Gasket tee fitting and gauge.

Seriously? If you don't know what your talking about, why answer? Btw, no such thing as a fuel injection pump.