I ran into a potential purchase my good friend is selling me at 260k and valued at 360k.  

Or potential contractors?

A rough 1% rule would suggest a valuation from 300k (which is near his asking price right now) to around 1mil.It may still be a viable project, especially if there is potential for the area, but I would seriously question how you got to your renovation budget, and more importantly, if the sources that you relied upon that got you to that figure are reliable and capable of taking on this sort of project.

There is a potential great deal I am looking at right now to convert a mixed-purpose building into a 4 unit building.

@Anna GreerWelcome to BP and congratulations on jumping into the forums.The City of South Bend commissioned a study in 2013 named "An Analysis of Residential Market Potential" for  Downtown South Bend.

Networking with experienced investors here would be a good way of finding potential mentors: https://www.biggerpockets.com/meet

You find a suitable t/b (potentially the person you spoke of) and assign the contract(s) to them.

Your clients would need to go take a look, and write up an offer by a certain deadline potentially.

I can't speak to everything you wrote about, but if I were you, the first thing I'd think about is your potential to expand.

I am ready to start cold calling, as well as handwriting and mailing lawyers as I gather potential seller info, but I don't know how to start the conversation.