1st Post and even more questions!

[jollygreen]

Hi y'all, I've been reading the site for the past couple of weeks and liked what I saw and decided to join since I recently (few days ago) bought my first Chevy. It's a 1967 C20 Fleetside (secretly wanted the '64 step but the guy was being a jerk about it) with a newly rebuilt 350 and standard transmission. A little bit about my backround? well.....nothing really. I am by far means no mechanic but I've been told this is the truck, and the engine to learn on so I'm quite excited. I'd like to do a few projects over the long Thanksgiving holiday seeing that I'll be able to take ample time off (about 4-5 days) and was wondering if y'all could give me a few suggestions. I'll list what I'd like to see accomplished.
I know I need to replace the fuel sending unit inside the gas tank, cheap fix from what I hear and that doesn't seem to be a big issue other than getting the bench seat down, any suggestions? (I was yanking on the thing and it barely budged) The second thing is the guy I bought the truck from gave me some 'newer' headers, the ones on there seem ok but they have what looks like rust and paint peeling off so I think I'd feel better with replacing those, and I'm sure I can manage that on my own.
The stuff where I start to wonder about is an altenator conversion? Why do I need it (I don't exactly know what I have), I have no worries about it, especially anything electrical considering thats my field, just curious. Also, the truck came with 3 fuel tanks, pretty sure going to get rid of the pasenger side one but the one on the drivers side under the bed is apparently going to need some cleaning. Found a kit online that is supposed to do it, just wanted to know what y'all thought about those or if I should scrap it and just try to find a new one. I think the kit is about 60 bucks but to get a new one would cost me about twice that I believe.
That's about it for now! I'm at work (oops) and will most likely post pictures later if there's any questions (which I'm sure there will be!). Thanks for all your help!