Took apart rear shocks to power-coat the chrome black..

Noticed the actual shocks seem pretty slack.. in fact, they don't do anything. Push them down and they don't return.

So in other words they seem had it, what do people do for replacements? Trying to find something local and I could only find these which are NZ$500  

http://www.motozone.co.nz/products/hard-parts/suspension-2/shocks/yss-twin-sh...

Seems weird to replace the springs and everything when the shocks are easy removed. Is it normal for them to come with springs?

..pretty fast, I can just stand it up on one end on the ground and push the top with my hand straight down in like, 1 second. Then they don't return.

Shocks will not return on their own, without the spring. It is the resistance to movement, either in or out, that the shock is needed for, to damp the movement of the suspension (spring).

Stock shocks suck.
I replace them with 12 1/2" Progressives.  I like the extra height and travel they have.
I have a set of 412's for the stock S40, and 418's on REX and the 1200 Sporty.  The 412's are cushier and the 418's handle better during aggressive riding.
The better quality shock will save your butt and your spine, and handle much better on the road.

I use the Progressive shocks because they are a good shock, they are  generally plentiful when searching on ebay and with a little patience you can get what you want for a decent price.
Of course, you can always pay retail and get them quickly if you want to go that route, but you pay more for that service.

There are other good shocks out there that will work well on this bike, but being an ebay junky I go for the  best deal available and there seems to be more Progressive's available there.

stock sportster shocks are a little light for us hefty folk.
you'll find you'll need the stiffest preload.
look for springs for the next heavier range... perfect.
I got 412's with the "1919" spring and have never touched them since.

I use YSS shocks.
Cant remember what I paid.
I have thrown the box away. But I found a poor quality pic of the box and it states LS650.
Same hight but smoother ride.

Hagons are cheaper here (in NZ) than progressives or YSS. I went for 31 cm, but they do have a standard-ish length option for the savage. You won't see it listed on NZ sites, but the importer can assemble it. Ikon in aus also have a standard length option for the savage.

I checked a catalog and it looks like the 412-4233c is an 11" long chrome shock with a spring rate of 115/155 lbs per inch of travel.  The Progressive shocks I have seen are all narrow at the ends like the Suzuki and come with rubber bushings and various sizes of hard bushings for the studs that they mount on.  

Nobody wants to say the 412-4233c shocks would be OK and then see you spend your money to get something that doesn't fit right or feel right.  The spring rate you have selected is what the Suzuki 800 Intruder uses and many people like it, others say it is soft.  Your weight will have some effect.

Buying from Ebay the seller might not have the bushing size you want but you could probably order some from Progressive or make some out of tubing.

Short answer is I think it would be OK but this post will at least bump up your post and maybe someone who has actually fitted these Progressives on their bike will see it and give you a better opinion.