[vujade]

welcome Diego...

First off if you only want to buy from the USA you will need to
contact Topline Autoparts in California... they have everything
you need to put wide Porsche wheels on your Super.

You will need a set of MAXX struts (these are narrower then stock)
you will need to have your drums redrilled for the Porsche 5 x 130 pattern
or you will have to buy drums that already have that pattern.
You will need 14mm press in studs for your drums.

In the front you should not need any spacers seeing as you have a 74
In the rear, you will need to run a minimum of a 10mm spacer if you
are running drums in the rear and you will need to grind the top of the
shock tower in the rear a little bit so that the wheel doesnt rub...

I had those boxster wheels on my 71 super and had to run a 10mm spacer
in the front and the rear, but the 71 is 10mm narrower in the front per side.