Fuel sending unit- steel vs. stainless, does it make a difference?

Need a sending unit for my duster, the two cheapest ones on ebay are $37/free shipping or $47 after shipping, the cheaper one is regular steel and the more expensive one is stainless, both from the same seller. Both are the correct 5/16 size for my 1970 duster with slant six.

Is the stainless steel one any better? I plan to swap in an 8 cylinder at some point in the future, hopefully within the next year or two, when I do I will probably upgrade to 3/8" fuel line as well so the sender would get replaced as well.