Need help plumbing fuel tanks

So I'm retrofitting a truck that had a single tank (square with everything on top) to standard semi aluminum round tanks. Both tanks have the small 1/4" fitting at the top (vent?), and two ports about 1/3 from the bottom. These ports go to tubes inside that curve forward and rearward.

I understand these are for crossover tubes. I also need to plumb the return.

Can I run the return to one set of ports and draw from the other port?

Would full tanks push back on a return line?

Do I need a check valve on the return?

And if so, should I draw from the port that curves forward....or rearward?

Thankyou

 

Ok thanks