Yeah, that's actually the bulk of my work. I have a network of about 10-12 builidings in my local area (I work in the midwest) and they just call me when a unit turn happens, a ceiling falls down, or something paint related happens.
I also work with real estate agents both investor/residential and frequently do paints for like duplex turnover or people moving into a house and want it painted before they move in.
I do like hallways, texture repairs, turn painting, exterior work, ect.
I have different ways I target people, I've worked in quiet a few different states and always did some form of sales, construction, insurance restoration work. It depends.
I've tried list buying (works in bulk, sometimes, if you hit the demographic correctly), my property management data I get is great because it's targeted correctly. Real estate agents are pretty easy to get because their contact info is usually public, GC and Builder info is easy beceause it's typically on their websites (i also have like 5k vendors in a list somewhere i rounded up because I was bored). It sounds like you're in the distressed property/contract assignment space. So, for someone like you, i'd imagine your best customers are people who have elderly parents or distressed properties? It's tougher to get ahold of homeowners because of marketing laws and their data isn't typically public.
You could try reaching out to the local government for tax lists - i sourced some building owners last week by looking up their parcel ID's and seeing which LLC is paying the taxes, and then reverse searched the LLC.
To answer your question, i guess what I would do to find investors (if i wasn't going to go networking) is i would reach out to a data supply company, and pull 5-10k building owners from the state I wanted to network with, then I'd hook it up to my automated marketing and just hit like 200-300/day until something lands.
With bought lists, you're looking at like a 1-3% response rate with a decent list (meaning, the people you are selling to have SOME sort of need for what you're selling). So, out of like 10k names you'd probably get 100-300 interested parties. Or at least knock open a couple of convos.
