Troy,
I contacted these:http://stores.ebay.com/Automotive-Style?_rdc=1
people to ask if they had a pattern for an IM roadster. They had a few 356 patterns but none for the original roadster or for an IM.
Their rep named "Rony" suggested that if I could send a pattern their shop could make mats to it, so my wife drew up some very good dimensional scale drawings on 1/4" graph paper, taking dimensions fom the original red mats that came with the car.
I scanned her drawing sheets into a single PDF and emailed it to Rony offering to pay additional for the custom work if successful.
We received the mats last week and they are dimensionally perfect reproduction of the red IM ones in that 'Calico' pattern shown. They also did an additional passenger heel pad because, she said, their design department so much appreciated the excellent drawings to work from.
Throughout I offered to pay more than their $121. shipped price and they wouldn't let me pay another nickel.
The upshot is that I'm delighted by this one and recommend the vendor to anyone interested. If you do contact them please let Rony know that "Ken S." recommended them to you.