Gst - input credit on stock held on the date of switch-over

I am a trader in Delhi registered with DVAT but not with Central Excise & buying material from Gujarat. If my basic cost is Rs.100/- on which Central Excise of Rs.12.50 is paid and CST of Rs. 2.25/- is paid @ 2%, then what credit adjustable against CGST, will I get at the time of switch over to GST. In fairness, since Central Government has received excise duty of Rs.12.50, this should be allowed to be adjusted against CGST liability when this material gets sold under GST and Rs.2.25 paid against CST should be adjustable against SGST. Please share provision under GST for this eventuality.