hi, i want to know if its possible to put a built ka24e-t block with a stock ka24de head?

yes, but its more complicated than just replacing the head

what do i need to do to replace the head with the block?

i have personally not done it but from my understanding you need the timing assembly and timing cover. also the sohc head bolts or bore out the sohc block for dohc bolts...prolly other things not to mention youll prolly have to get it tuned since youll be running such high compression.

ok-guys-here-it-is-proof-t40742.html
I've seen this question being asked a couple of times, but I've found the thread above to be the most informative on the matter. The forum upgrade messed it up pretty bad, pictures are mostly gone, but it should still be readable.

In short, if you're asking whether it is a simple bolt-on, plug-and-play matter, well, it's not.