Stack-up is the amount of vertical space that your mainsheet system takes up when sheeted block-to-block.
Another way to measure it is to rig the boat, sheet the main in as far as it will go (block-to-block), then measure the distance between the boom and the rear crossbar.
That measurement with the current stock, low profile mainsheet system is less than 9".
The jib halyard should never limit your mast rake. The forestay is usually the limiting factor. On older boats, you can just add another adjuster to the forestay to make it longer. Put a piece of shock cord between them to take up the slack in the forestay when the jib is up.

Here's what I would do with your boat:
1) Rig the boat
2) Sheet the main until it's
almost block-to-block (maybe 4" between the blocks - don't oversheet so that the leech of the sail hooks to weather of the mast).
3) If you can't get it in that far, loosen the jib halyard until you can
4) If you can sheet it in that far easily (leech of the main is still open - not in line with the mast), tighten the jib halyard.
You want to be able to stand behind the boat, sheet in the main and have the leech line up with the mast
before you go block-to-block.
When you're sailing, the wind will blow the leech open, allowing you to sheet in that last little bit without hooking the leech.
Here's what a hooked leech looks like: (it's a 17, but the principle is the same)

That little strip of red you see above the mast is the leech of the sail. This sail is oversheeted. Oversheeting is
slow.