Trump can simply get "a small loan of a million dollars" from his dad if he decides to build up anything. I imagine he'd want to construct some major sports stadium somewhere. IOTL, he got NYC's Wollman Rink renovated at a quicker pace and lower cost than it was taking before he got the project. Maybe something like that happens here but for some sports stadium?
I'm glad you are enjoying this TL! Thanks!
I remember getting a fun fiction book, "The Man Who Brought the Dodgers Back to Brooklyn," that I got for Christmas in '82 or '83. Now that I look it was written in early '81, but I can still see one of the guys - who is a former minor league player - being modeled partly on Trump and being the one to develop the idea of rebuilding Ebbets Field.
As for what he'd do TTL, Most stadiums in New York (and New Jersey with the Meadowlands) are rather new, save for Yankee Stadium, which has been renovated recently (mid-'70s). But the White Sox wee in need of a new one with Comiskey Park over 70 years old, and there was danger of them moving in the late '70s till the "long count" of the legislative session went past the deadline to approve a new stadium.
Perhaps here, Trump starts his work in the "second city" where prices are a bit cheaper, and develops something for them. (Which is a lot prettier than TTL's park - originally the old fashioned style ballparks started with Camedn Yards in 1992 but the design was offered to the White sox, who turned it down.)