thats a terrible idea, I hate to be the one to say it but that swap just isn't worth the effort
You need the turbo model, the turbo ecu, the turbo compression ratio, the turbo piston oil squirters, the turbo everything. Toyota didn't put any of the good stuff in the NA engines, and I am pretty sure they still weigh what an IRON LSx weighs. It won't make the turbo any cheaper, and it does make everything else more expensive.
with 5-7k your best bet is to buy a bunch of cheap cars, fix them up, drive one and sell the others for profits, until you have 15-20k to drop on a proper swap or FIND the 240sx you want somebody already "built somewhat" with a stock (hopefully reliable stock) drivetrain. The buying/selling more or less is what I did by accident.
i.e. after I sold my white 240 and had NO car to drive (Im a 1 car guy) I picked up a POS sentra for 600. Had it for ONE DAY and hated it so I sold it in CL for $800 the next.
Then I found a Corolla auto for 800. It had some kinda weird wheel bearing noise so I sold it a couple days later for $1500.
Then I finally decided (4-5 days went by) I wanted a truck. a Tacoma was perfect for an LS/2J swap (at the time I was tryin' to figure out what to build). So I got a little pickup for $1900 decent enough.
https://www.tacomaworld.com/threads/i-might-be-picking-up-a-98-tacoma-tomorrow-couple-quick-q.469152/page-2#post-14137387
Started making my plans to swap the truck (I work fast) and the next day I get a message on the truck "NO TRUCKS ALLOWED" turns out my place dont allow trucks. So... What did I do...
Sold the truck for $2600 and realized I had better find a 240sx because its the only old car worth a
[email protected]#)(* apparently. Plus I knew what I wanted now: A truck engine in my non-truck car. So I can start the thing and have everyone looking out their windows every morning for a 'truck' that shouldn't be there! hahaha....
Then I realized I would still need a cheap car to drive anyways if I am going to swap an LS into anything. My org. plan was buy 2 tacomas and swap 1 use the other for driving while I swap. But no trucks so... I picked up another corolla this time $1000 and its amazing. New tires, A/C, manual trans, 33-35mpg zomg its purrrrfect. And it will be worth 2k~ when I decide to sell of course.
So you see how I put away thousands of $$ just by accident trying to find the correct car to swap. If you are good mechanical nature, then you can do it. I cleaned the #@(*@# out of the engine bays and interiors to get that profits.