I'm from Tn my neet score is 263 and sc community rank is 420 I have been called for councelling on July 7th can I expect a gov seat?plsrepl

You would most probably get a seat under SC category. You have scored much more than usual cutoff in Tamil Nadu. Last year, the cutoff for SC category was 193.
So, congrats and all the best.
Meanwhile, you can visit following link to know about category wise cutoff scores in Tamil Nadu last year to have a fair idea about your chances of selection.
NEET Tamil Nadu cutoff

Hey.
Here is a list of all government medical colleges in Tamil Nadu and their respective cut offs in 2017 for the SC category under the state quota.
You seem to have a fair chance for for admission in a government medical colleges considering your marks and category.
ESI-PGIMSR, ESI Hospital, KK Nagar, Chennai
7,455
206
Kanyakumari Medical College, Kanyakumari
213
Rajah Muthiah Medical College
193
Coimbatore Medical College, Coimbatore
3,800
264
Govt. Dharmapuri Medical College, Dharmapuri
6,124
222
Vellore Medical College, Vellore
240
Theni Medical College, Theni
6,401
218
Thoothukudi Medical College, Thoothukudi
6,987
211
Mohan Kumaramangalam Medical College, Salem
5,243
236
K.A.P. Viswanatham Govt. Medical College, Trich
5,011
239
Tirunelveli Medical College, Tirunelveli
4,578
247
Thanjavur Medical College, Thanjavur
4,503
249
Stanley Medical College, Chennai
2,190
314
Madurai Medical College, Madurai
3,236
277
Kilpauk Medical College, Chennai
2,687
295
Madras Medical College, Chennai
1,407
353
Chengalpattu Medical College, Chengalpattu
3,812
263
Thiruvannamalai Medical College, Thiruvannamalai
6,592
216
Govt. Medical College & Esic Hospital , Coimbatore
6,989
211
Govt. Medical College & Hospital, Pudukottai
7,386
207