You can execute gift deed to transfer 50 per cent share in favour of son and 25 per cent in favour of wife
2) gift deed should be duly stamped and registered
3) all co owners would have clear and marketable title
4) your second son consent is not necessary
5) co owner can make application to bank for obtaining loan for carrying on construction on the property with your consent and that of your wife
6) bank would insist that you and your wife be co applicants for the loan
7)you , your wife and son would be co owners of the property
8) you can execute will bequeathing your 25 per cent share to your wife
9) will should mention that in case your wife predeceases you then your 25 per cent share will devolve on your son
10) similarly your wife can execute such a will
11) your son as co owner can sell his share to third party