In my humble opinion the price for this particular 240 is set just a little too optimistically. I has a few things working against it as far as 240s go
The rust. Yeah its a small amount but people who are looking to buy 240s havent yet become accustomed yet to the idea of fixing rust and will rather wait it out for another one. The supply hasnt dwindled enough yet for people to consider it as a job worth doing like other cars such as Kombis, old holdens etc. It also looks like this car has had a windscreen in the past as the seal looks aftermarket. The rust around the bottom could be a little worrying for a potential buyer as this could indicate water intrusion and rust in other places downstream of the A pillars such as the floor. The colour. 80s metallic silver 240s are kinda meh. The paint fades, it peels and can be a bit of work to keep looking fresh and deep. A solid colour 240 of the same year will generally have a better quality paintjob still on it today compared to their metallic brothers. The year. 1986 - 1987 was a weird year for 240s in terms of their engine management. They got LH2.2 which was a stop gap solution until the far superior LH2.4 came along. Owning an LH2.2 240 can be a little bit of a chore with things like bio degradable wiring harnesses, weird fuel pressure regulator mount location and troublesome AMM's. You also have the imfamous hall effect sender which can randomly just leave you stranded. Compared to changing a CPS a hall effect is a bit of a paint in the butt. The manual. Yes for many is a desirable upgrade but in 2022 ive found so many people shy away from manual transmission cars. I struggled to sell a subaru L series wagon. Not because it was a bit of a beater but because of the manual transmission. I had atleast 5 people back out because they decided they didnt want a manual.The historic rego. This is pretty limiting for someone who may want to use it as a daily/semi daily. The rust is going to be a big red flag for anyone who may want to put it back on full registration as it will need to be inspected again. The new owner may go from needing to repair rust to needing to repair suspension components, emissions equipment and the list goes on. Seeing those historic plates is going to make people think about all the shit that could be broken and inbetween them and obtaining full registration.
Your car is also dirty. Go get it cleaned and make it shine as best as it can. A clean car always attracts more interest and less scrutiny by those interested. Depending on how quickly you need to move it on you might be better off just lowering the price or lowering your expectations of how quickly it will sell and hold onto the price and wait it out for a serious offer.
None of this is meant to offend so dont take it that way. You just seemed curious to why your 240 wasnt selling and these are the reasons I can see as someone who has had a 240 since 2007 so has seen a few come and go :)