Putting the 16v head onto an 8v block would be a lot of work.
If all the water and oil ways line up (I suppose some variant of the 16v head will line up) you will be lowering the compression ratio because the 16v combustion chamber is larger. You will then probably need to change the pistons or machine the 8v pistons for cutouts for the valves.
You will then need the whole 16v intake system, throttle body, and air box assembly. Crank sprocket and intermediate shaft, oil pump, and crank trigger wheel etc will need to be changed, as well as sensors and probably sensor positions will need to be changed.
ECU and associated wiring will need to be changed.
Then consider changing to the stronger 02A gearbox and either cable clutch conversion or complete hydraulic clutch.
If you wanted to do a turbo conversion it might be a way to go but the loss of compression ratio plus all the work and effort wouldn't really make it worthwhile. It would be loads easier to transplant the complete abf lump into the car.
Probably loads of stuff I've missed in the above as well.
Paul
