Good going!
You asked about the DOHC head, do you want to put it on your car's engine? A DOHC head cost around Rs.15K, with accessories (Manifolds, Pulleys, timing shield, water pump, nuts and bolts) around Rs.25K. You will need new timing belt,pulley set and head gasket for around Rs.17K. You will also need ECM and wiring costing around Rs.10K. Labor costs will be around Rs.8-10K (Electrician + Mechanic). There will be frequent visits to workshops until all the issues are settled.
If you can get a complete DOHC engine (costs around Rs.35K), still you will need new timing belt and pulley set (Rs.15K) and add another Rs.10K for labor. This engine will put additional 60Kg on the front suspension, you will need Cielo's suspension, although this is optional, but you will have frequent shock failures, since the springs are not able to sustain the additional load they are not designed to bear.