I have a dsa full size sa 58, any good ways to:
1) add a light to existing handguard
2) sling it for a tactical 2 point
3) should I rattlecan it
4) I'm a tool and die maker and could re barrel it for a 16 or 14.5 barrel, is it worth it?

I personally like the 436mm length barrel (a bit over 17").  It's the shortest that FN offered outside of special orders. 

I mounted an MLOK rail section through the vent holes, but it did require some work with a file.

I use a BFG VCAS on mine.  I have a South African handguard-mounted sling swivel up front and a standard one at the rear, but ideally I'd like the rear swivel to be mounted on the side.

Not sure what your configuration is (SA 58 comes in a variety of configurations), but going lightweight if yours isn't is a plus.  Replace the trigger housing, top cover, trigger guard, PG nut, etc. with alloy parts and get the titanium combo device offered by DSA.

An extended Commonwealth-style selector combined with the SAW grip makes for ideal ergonomics, IMO.

I wouldn't bother with spray paint unless you really want it.

I opened up my aperture (on the standard tangent rear sight) to make it like a ghost ring sight, which I like better than the narrow peep.

If modernization includes optics as you see it, you can't go wrong with a DSA mount (I just wish they were lighter).

Regarding weight, another major area for savings is magazines; get alloy magazines or Moses polymer magazines (if you can find them).

Aim Sports makes MLOK and Keymod handguards, and there's the VLTOR CASV as well.

There are more radical options, like the ACR-style stock, if you want to go such a route.

Don't get much more modern than this.

I'm moving towards more of a "assault rifle" look, I have a couple of spr' s all ready

That looks really heavy and cumbersome.

Did you really just use the A word?

Nice rifle man

Yes it is a big, heavy sucker.
It's a tack driver and makes a great SPR though.

Sure it does...

You trying to say your FAL is ''more modern'' than mine? That's not right.

Very nice!

  

That thing is sexy