your request for 19" old school wheels sounds like an oxymoron. :-) You may want to check the fb group "I was in a minitruck club back in the 80s and 90s". I hope you find some.
18s & 19s ARE considered old school these days. You're best bet is probably craigslist. I see Rhines & guidos every now and then, mostly 18s, but 19s pop up occasionally.
maybe it's a matter of how old you are and how long you've been into minis. I'm 39 and been into minis since 1989. I dont think of 18/19s when I hear old school. lol