https://classiccars.com/listings/vie...illinois-60060
Not exactly what you want, but in your price range.
https://classics.autotrader.com/clas...bird/101069100
A nice 400/4-speed will be higher, unless you luck across a super deal, either from a guy desperate for money or one who doesn't know what his car is worth.
https://classics.autotrader.com/clas...bird/101069414
https://classics.autotrader.com/clas...bird/101073966
I've also noticed that the cars are usually much cheaper if they do not have a 400 engine. So, you might wanna consider one with a nice body & a 350 Pontiac engine. If you want more power, you can have a 400 or bigger engine built, later.
https://www.carsforsale.com/vehicle/details/49745966
Also appears that most of the 400 cars have TH400 trans. Might consider buying one of these, then have it swapped over to 4-speed manual at some later date.
https://www.cargurus.com/Cars/l-Used...ting=218379840
https://www.cargurus.com/Cars/l-Used...ting=230695881