i did a top swap over a year ago now, dont sweat it. not a big deal really. buy new bolts, or head studs. you'll need a degree gauge too if you use tty new bolts. a long breaker bar is a must or a pipe on the end of a short one. i swear you think the bolts are gonna snap when you degree them, you've never made a bolt so tight in your life and not had it snap lol
you also want to take a old head bolt, cut a groove in the threads on two sides then put it in each head bolt hole in the block and remove it, this cleans the threads out so your tq'ing is proper.
i used felpro head gaskets too.