import the template without worrying about the size.
select all (ctrl-A)
then 2 ways of doing the stuff. 1 precise, the other not

1) hit shift F8 (this will open the transform window)

you can select the size you want precisely, if you click on the litte chain, the modification will be forced to height/width ratio
2) either select in the object menu the submenu transform and then scalling (not sure of the names) see pic attached it is french but menus are locate the same way


it will open a window that allows you to resize the selection by the % you want.

hope it helps