You cannot possibly document any link or prove it based on fragments or general information -  you would need to research all available historical and ethnography sources  from here and Albania, look for migrations, document the origin of each family, branch and surname  - a research like that could only be carried out with visits to original holders of  these documents and records -archives , would only be possible with extensive knowledge of all local languages as well as those that were in official usage , and would be in time and knowledge needed equivalent  to doing a PhD thesis on this subject.

I am still baffled as to why are you researching all possible variants of these *maybe* connected surnames  -  I know of a few such successful researchers who made an effort to do that, and they have spent decades documenting their migration and origin theories of a particular surname or a family.

If you are interestred in figuring out where your direct ancestors came from and what their origin was - both immediate one before emigrating and the more distant origin of a clan or a surname please give us more concrete, specific data on the last known ancestor you know of .

I promise you a valid srtarting point for your research and direction where to look for records based on facts. if you are for any reason uncomfortable about sharing private information, you can send me a PM or an email - [email protected]. 

If you are a member of SGS Rodoslovlje I will  contact relevant archives on your behalf and assist you further.

As for the question you asked- the area you are wondering about (Skadar) has a history of intertwined tribes and origins, and documented Slavic presence even for the period of their initial, pre-Christianic times arrival to the Balkans.

@ the two links you posted: the first one - http://www.geni.com/surnames/bori%C4%87  is a copy  from a second-hand web source ( I call these *Balkan crap genealogy*) - usually run by people too inclined to document surnames as only as belonging to their own ethnicity - when you see wording like* ...surname X is mainly Croat/ mainly Serb..." best avoid it - ethnicity that was attached to a surname can only be determined by looking at original documents and needs to be determined for each and every family and smallest village of origin separately .

The sentence "Borići su uglavnom Hrvati, dobrim dijelom iz okolice Senja, a rjeđe su i Srbi (iz okolice Vinkovaca)"

translates as  "BORIĆ are mainly Croats, in large part from the SENJ area, and more rarely Serbs from VINKOVCI surroundings".

Avoid such shady sources in the future if you are keen on working with facts.

- here are the ethnic Serbian BORIĆ families  from just one original source  that can  be documented in Ličko-SENJSKA županija, in VRHOVINE and MOGORIĆ,  so definitely in the SENJ area for which the  link claims otherwise:

(source -database of The Serbian business association 'Privrednik'  ('The Merchant') and the ethnic Serbian children it sponsored)

Second link - http://www.familycetic.net/sources/milan_karanovic.pdf - is to a study by a priest& later ethnologist-curator  MILAN KARANOVIĆ (1882-1955)- he published over 150 articles on ethnology and origin of families,  He mentiones the BORIĆ surname that  is found in LIKA  in Croatia after migrations as one of the branches of the original BOGUNOVIĆ clan.  I would consider him, given the amount of field research he did, the resources he had at his disposal (church vital records and original documents) , and his life choice of science over priesthood a reliable source.

Lastly I was reading occasionally a historical book in albanian. In this book it was a phrase written about an earl Boriçi that has moved from Albania in Italy during the 15-th century. It seems that people surnamed Boriçi have existed in Albania at that time. I am investigating more about it.

I wrote a letter to the Split archives (Croatia), but never got a reply. I wasn't really expecting any. No leads from here. Any thoughts?

I finally received a letter from the Croatian Archives, but rather inconclusive:

With reference to Your inquiry concerning information on researching the history of Your family, we can inform You according to our referent sources that we couldn't find the family name Borici in the territory of the Republic of Croatia. We found the name Boričić and Borić because these family names were and still are quite frequent in Split and nearby.
In the Croatian State Archives we keep microfilmed birth, marriage and death registers of parishes in Split, but we recommend You to search through the registers from 17th to 20th Century on the official website of the Genealogical Society of Utah in order to find more information on Your family ancestors ( http://www.familysearch.org/). Please try to identify the Croatian version of Your family name as well as names and dates of birth and death of Your family ancestors in order to search through the registers online as easy as possible.

Sincerely,

Head of Reference Service