I haven't buildt the Sig 4*, but I have built other kits. If the spars are not unreasonably bent you should be ok.

I'm not sure about the wing build on the 4*, but most kits. You pin the top spar (top of the wing, but you don't glue yet) to the plans straightening and holding in place to match the plan. Set your ribs on this spar and then set the bottom spar on top of the ribs and glue. The spar that is pinned down hold the ribs straight.

If both spars are bent, I turn the the bends opposite each other. That way they pull against each other. Then, usually you will glue the trailing edge on, and then the leading edge or sub leading edge. This too will help hold the wing straight.

Flop the wing over, pin the glued spar to the plans, and then glue in the top spar (actually the top of the wing).

I hope this helps. If the spars are unusually bent, I would go to my LHS and get new ones. They are usually only
a couple bucks each at most.