Hang on just a minute there! I'm doing the same conversion and ran into the following problems:
1 - The 3 bolts that hold the rear end of the spring plates are a different pattern between Porsche and 1303 (ironically the Porsche a-arms are the same bolt pattern as swing axle bugs - go figure!)
2 - The bolt holding the a-arms to the brackets by the gearbox is much bigger on the 1303 than the Porsche, but I've been told that you can put 1303 mounting bushes into the Porsche arms.
3 - as a 944 is a fair bit wider than a bug, if you fit the Porsche a-arms, brakes etc. your rear wheels will be 6 inches further apart!
Now I thought all 944 a-arms were alloy, but aparently you can get steel ones too. There may be no pronlems with the steels, but I'm rather in the **** with my alloy jobbies.