The numbers in parenthesis are the latitude and longitude in degrees and minutes.
In the search for the village of Puszkance one possibility is Paszkance (Polish) in the gazetteer  in the district wilenski (Vilnius) in the district Bijuciszki of the 3rd Polish region, 7 1/2 miles from the local administration of Malaty (Moletai) (55 14 25 25). Paszkance appears to have been 40 to 55 miles SW of Zarasai.
The best guess from the JewishGen ShtetlSeeker  is Poškiečiai (Lithuanian) (55 58, 23 46) near Kundrociai. My coworker on the family tree, Olga Zabludoff, lives in Washington DC and went to the Library of Congress map room to investigate. To find this village on the old maps of western Russlands  from about 1900, they had to add 17 deg 40 min to the longitude to convert to the Ferro meridian because the Greenwich meridian, although established in 1884, was not used for these maps. They found it on map N 18 (Szadow) spelled Paszkance . MapQuest shows the modern name as Poskeciai (Lithuanian), but it is also spelled Poskieciai. The only problem is that this village is 100 miles west of Zarasai, not 50 miles. Beider says "This village can not be the same as Pushkantsy/Puszkance. The Shadov/Szadow area was within the Shavli (Szawli, Siauliai) district. The Novo-Aleks. district was separated from the Shavli district by the Ponevezh district. So it is a different village."
In the Earth Sciences Map Library on the UC Berkeley campus I found a book of Russian place names  which listed both Pashkany/Paszkany (54 36, 26 01) in Belarus 80 miles S of Zarasai, and Poskaiciai (55 23, 23 18) 120 miles W of Zarasai. This UC library also had the complete set of maps of western Russlands . I found Pashkany on map S 23 (Wornjany) as Paschkany, and Poskaiciai on map M 20 (Rossienie) as Paszkaicie. On the web site Map24  I searched for Pashkany and found it 20 miles N of Kaunas. I searched for Paszkance and got Pancekiai, yet another town, 20 miles SW of Kaunas.
Beider concludes "None of them can be the source for the surname Pushkantser. Of all villages you found on various maps, none corresponds to Pushkantsy/Puszkance from the Novoaleksandrovsk (Zarasai) district."
A possible modern village coresponding to Puszkance/Puszkancz in the Birzai Kahal is Puškoniai/Poškoniai (56°11' 24°26'), 77 miles WNW of Zarasai. I found this village on map P 17 (Birzai)  as Paszkuny. However, Beider says "I don't see how the sound "ts" (German tz or z; Polish c) could disappear and it is clearly lacking in the name of this village while it was present in Puszkan-C-e. So Puškoniai/Poškoniai is unlikely to correspond to Puszkance, while it fits perfectly to Paszkuny. That is a different village and could not be the source for Pushkantser."