[sleepydsm]

Use a dremel and smooth out the knicks in your pistons. I made over 550 awhp with stock cast pistons with knicks on them.

If you spend $100 to get that "new" head from your friend, who is to say the valves aren't slightly bent in that, or it has shitty valve stem seals (which will cause your car to smoke and use oil),

If money is an issue for you right now...
Buy your friend's hopefully good head.
Get a stock headgasket, use "Copper Spray" on it (you can get it at any autoparts store: it helps the new headgasket seal better).
And get standard ARP headstuds.

If you can spend a bit:
Bring your head to a machine shop, get it repaired RIGHT.
Buy a stock headgasket OR a fancy one (IE $250 Felpro Permatorque)
Buy standard ARPs or fancy studs (IE $200 ARP L19/ MAP H11)