I am answering based on memories of long past events but around 1962 I purchased a Sheaffer Fifetime cartridge pen for $25 at the MIT bookstore. It had a "signature stub" nib which I would call "italic" as there was a big difference in width between a vertical stroke and a horizontal stroke. The nib was definitely tipped and was very smooth, quite unlike the inexpensive Sheaffer calligraphy nibs. My nib was inlaid and looked just like the inlaid nibs used in the Targa. So, it may be possible that is what the broader nib shown is. I think Sheaffer discontinued the Signature Stub long ago but I do not know if its life overlaped that of the Targa.
After graduation I worked for many years in a lab that was very hard on the pen. It made many trips back to Iowa for repair of damage that often was clearly the result of abuse. I offered to pay but Sheaffer always fixed it for free. I still own the pen in name, anyway, but I doubt any parts from 1962 remain. In one of its last trips to Iowa I compalined of inadequate feed. The pen probably just needed a good cleaning, but instead Sheaffer replaced the nib with a broad. What a disappointment! It's a wonderful broad, but I don't want a broad!-(