Home loan in Section 54f where not using the full Capital Gain in buying a property

I have made a capital gain of Rs 50 lakh on shares where the overall share value is 70 Lakhs(amount received by selling). I want to buy a house within one year of share sell,  for 40 lakh. Can I apply for house loan(I will not use the sell proceeds for buy-ing house and only use 15 lakh from that and rest 25 lakh as house loan) and still use section 54F for tax savings. The shares were part of An employee stock ownership plan (ESOP) of a foreign company(USA). 

For 54 f can I save on 40*50/70 on LTCG or it will be 15*50/70