Hi Gary,
First, great to hear you have a '69 912 that was a SWT! No question the factory produced them, at least one piece of 1969 factory literature still called the 'Version II' HWT
"an extra-cost option", and notes
"Rear seats are included in Targas with fixed windows." Here's a link:
PCA 912+912E Register Facebook image . And there is other factory literature showing SWTs with the 1969 and later Targa bars with ventilation slots.
As of now there are roughly a couple dozen listed on the 912 Registry Owners List:
912 Registry Owners List 1969 Targa, VIN 0000-0400
Speaking of SWT parts, in 2013 Porsche announced a new batch of the handles; brace yourself, then look at page 4 of this product booklet with the price listed:
Porsche Classic Product Highlights 01-2013
For a little inspiration, here's an image of a nice Burgundy 1969 912 SWT:
PCA 912+912E Register Facebook image
Keep us informed how the resto progresses!