Stack pack installation

[Harveyhall]

I am looking for pros and cons from experienced users of stack packs.
I have purchased a North Sail stack pack for my 2005 C36. At present time I have lazy jacks fastened to the mast.  Two questions:
1. Is it better to use existing pad eyes for the adjustment line or to use a new pad eyes fastened to the bottom of the spreaders. (I have seen them set up in both locations-on the mast and on the spreaders)
2. What is the optimal height of attachment of this pad eye and turning block?
Thanks for your advice in advance.

[symphony2]

Did North Sails not provide fitting instructions? The normal height for the lines is 70% of the mast height - not exact but an indication as that may conflict with the upper spreaders. Personally I don't like using the spreaders to attach the blocks and if you have pads already on the mast at roughly the right height then perhaps best to use those.

[Harveyhall]

No fitting instructions provided.  I am thinking a mast pad eye and block may be the best. This may keep sides of the pack close together and away from any stays. It’ll see if there are any further recommendations on height of these blocks. Thanks