Recently bought a mk3 Astra 5dr 1.4 8v, single point injection so very slow, would like to take out and put in 1.4 16v engine, not sure on whats needed (ecu's, gearbox etc) and what will cross over to 8v loom, any help will be greatly appreciated.

Wanna keep the tax and insurance cheap so thats why i want 8 more valves, had a 16v lump in my mk4 astra and was quite impressed.
thanks for reading guys, hope to hear some ideas soon.