Are you sure that's going to be resistant enough to surge mounted like that?
With a small tank like that you need all the capacity useable. If running injection you will be better off with a small aluminium sump on the bottom fed through a few holes in the base of the main fuel tank than using the Omega internal pot and pump.
Feed and return lines into the sump so it isn't prone to "sucking air" even when cornering with a practically empty tank, and probably an external filter and fuel pump. - IMHO, of course.
Either that or the arrangement I have - a low pressure fuel pump (facet) feeding an external surge pot which in turn feeds a high pressure pump.
Anyway, regarding the fuel level, you'd be better off getting a sender that matches the gauge, IMHO. However, they are all basically just a variable resistor, that one included, by the look of it. It might have a non-linear response to cope with the odd shape of an Omega tank, I guess.
It also needs to be the right resistance value for the gauge, too.
Try putting a multimeter on ohms across it and work out the min. and max. resistance and try to figure out if it's linear or not.
Kevin