Hi there, 
70 marks in JEE mains for SC category roughly translates to around 5,500 category rank. 
The choices in Government and semi-government colleges that are still open to you are:-
1) BIT Mesra (ECE)
2) NIT Hamirpur ( Chemical Engg.)
3) NIT Rourkela ( Mining Engg. /MSc Physics or Chemistry / Ceramic Engg.)
4) MNIT Bhopal ( Metallurgical Engg.)
5) IIIT Kota (CSE)
6) MNNIT Allahabad (Biotech)
7) NIT Jalandhar (ICE, Biotech)
8) NIT Delhi (ECE)
9) IIEST Shibpur ( Mining Engg.)
10) SVNIT Surat( MSc Physics / Mathematics)

So these are some of the choices available to you, but you should better wait for the result to be officially declared and then there can be better predictions on the basis of your real rank.
Hope it would help.
Thank You.