Project Black Out, 1981 stepside... need help planing

[kserieskid]

New to the forum. already had a ton of help just reading some of the posts on the site. Right now im starting a new project. The truck is a white 1981 chevy stepside. It is from Nevada and came to NH in may. some guy had it and lost interest in it so I picked it up on the cheap. Truck is legit cleaner than a lot of the newer trucks out here.

my plans:
Drive the truck in the summer and very little in the winter, only when the roads are dry
needs to tow a small load ( 2 place horse trailer and a small car from time to time, me and a buddy flip a few cars a year)

what has been done so far:
complete cooling system
power steering lines
blower moter ext
tires good year wranglers on 15inch rims, wikid cheap from wallmart
inner tie rod
u joints for rear
transfer case output shaft seal
re wire the whole dome light and replace with some leds

big current plans:
undercoating
rebuild front driveshaft
window channels and door seals/tint
fix temp gauge

summer plans:
axle swap
built 350

so in preparation for the axle swap here's what I have

I own a 3/4 ton that is getting junked in the spring with a semi floater rear axle that im just gunna drop in and use till it blows up. just because I own it already and have done a swap with a semi floater so its familiar to me.

my question right now is will the axle shafts and spindles fit on the half ton axle that is already in the stepside? the axle in my 3/4 ton is not in the greatest shape and I was wondering if I can just swap spindles and shafts so I don't have to buy two new sets of gears

thanks this is all in prep for the summer I really like to plan my projects out to save money

thanks, kserieskid

first two pictures are from the week I got it
last one is the just the other day, slowly taking all the stupid chrome stuff of and blacking it all out.
also going to make a custom headache rack