I will make a new forestay that is long enough that the it will be as long as a stock forestay with the ten hole adjuster so I can use the seven hole and avoid buying a new one. So maximum rake on the mast. .
Conventional wisdom says you should keep all your wires the standard length. The time will come that one of them breaks at a regatta and there will be lots of standard spares around, but unless you have non-standard spares, you are out of luck. We have been breaking a lot of wires recently...even some that are less than a year old. Two Waves last weekend. Perhaps it is offshore wire...who knows.
At any rate, you will always want the capability to adjust, such as when you try a different sail...they aren't all the same. Pop for the 10-holer.
What kind of rudder housings do you have? I wouldn't drill until you get your mast rake set where you want it.