<VV> gas tank

[Landis, Art MR]

My '63 Monza project basket case is starting to come together now, thanks to
a lot of your insight.  The guy I bought the car from included a bunch of
parts.  One such part is a gas tank to replace the one that has a 1" hole in
the bottom left corner.  This replacement tank is covered with a yellow,
vinyl-like coating (perhaps a sealant?) on the outside.  I took the fuel
sender unit out for inspection and it's coated with rust.  The tank itself
seems to have some sort of crust-like substance (perhaps rust?) that coats
the entire inside of the tank.  Would you even bother to fool with the
"replacement" tank? I'm very limited on my budget and want to make the best
out of the spare parts I have available before I spend $.  What do you think
about having the original tank welded?  Also the original fuel sender looks
a lot better than the rusty one!  Thanks for your help.