Hello aspirant, hope you are doing good.

So, firstly congratulations for your score in NEET, although it isn't outstanding but I'm sure you still tried your best, so kudos to your efforts. As per your question, the cutoff for Siddha government college as of last few years have been 530+ in general category, and atleats 500+ in other categories, as an approximate value. So, as you can see, you don't really have much chances of getting a seat there because its a matter of 200 marks in between, and that's  alot.
But you dont have to be disappointed, you still have other options in your hand, you can use our NEET college predictor tool to find out all the possible colleges you can get :

https://medicine.careers360.com/neet-college-predictor

Hope this helps you, Good Luck !!