Universal Fuel level Sender unit Question

There is probably an easier way to do this than I did but I could not figure out the math/resistors needed to make it work. So, I did this to a sending unit from a '74 Newport. It was a leftover from my demo derby days. The unit had a 3/8 outlet and a 1/4 return. My stock sender('63) was only 5/16 and had no return, so this was a two sided upgrade. I had an old Moeller Marine fuel tank with a 33 to 240 Ohm's sender in it. You can buy the sender online for around $25. I traced out the '63, the '74 senders and added the Moeller sender to the modified '75 unit. Had to file the round hole from the O.E. sender terminal square to fit the Moeller ternimal. I also used some 2 part epoxy around the terminal insulator on the outside for a little extra insurance. Once you get the swing figured out you can make the float arm whatever length and shape you need it. I reused the Moeller float and recycled some of the O.E. float arm. I used a small piece of copper tubing and crimped and soldered them together. It took a little time but it works perfect. After the first go around I modified it more by unsoldering the original 3/8 outlet and replaced it with a new piece of 3/8 flared to 37 deg. with an 6A-N fitting on it. Just some food for thought.
Larry