My boat is 46 years old and except for turnbuckles, my rig is not adjustable. I'm in the same position you are.
You say you have a non-original "rollerfurling system that has 3 extra links on the bottom of the main-stay". When you say main-stay, are you referring to the forestay that your jib flys from? If so, I suppose it's possible that a previous owner altered your mast to be leaning too far back by adding length to the forestay with those links. Removing a link may help.
At any rate, to induce pre-bend in a rig like ours, you need to tighten the lower shrouds a bit (equally). Don't go all Mongo on them, they aren't supposed to be bar-taut. This will help shape the luff.
When you sight up the mast, you should see the top 1/3 of the mast slightly curl aft.
When you get sailing, try posting some photos of your sail and trim. That will tell us a lot. Shoot from under the boom, looking up.
S/V Old Shoes
1973 Pearson 30 #255