More power to my hardbody.

[727G35]

I just got a 1997 hardbody with a ka24e and a 5 speed manual transmission only 68k miles.
Now I want to make more power.
1. if I was to turbo this sohc engine how much hp can it handle?
2. If I want to make it a ka24de, do I have to swap the whole engine or can I just put the dohc head on my block?
3. I read that sr20det engine and transmission will bolt to the hardbody since it's a 4cyl engine, can I bolt the sr20det to my 5 speed transmission tho?
4.What engines can bolt to my transmission?
And other power ideas please share!

[727G35]

I think I'll do suspension and stuff and just turbo it.
I can bolt on a turbo kit for the 240sx with the same engine?