The starter clearance deal, at least on mine when the 016 was in, was that the starter would foul on the chassis. So, I cut a rectangle out that perfectly fit the starter. However, this doesn't need to be on the Porsche box cars since the starter is mounted to the transaxle on the back (*I think*). I can tell you exact dimensions of the 016 clearance hole, and location, but I have not (and didn't intend to) make a "plate" to make a cavity out of the hole.
If you are talking about motor mount holes, well, there is no way I'd drill those and try and mount the motor without the adapter plate and transaxle in place. In fact cutting the clearance hole for the starter is a bit iffy too since dimensions could easily be off 1/8" or so. Somehow I managed to get mine to fit really well, but it is tight. I can easily measure this AM if you like. Pictures are on my build thread too, and those can be used for reference once I get the measurements.
R