Your getting tucked. I can do head gasgets in 3 hours (Drive in drive out) its a easy as job and the parts are cheap. Id say get a gasket set and do all of it, Do it once and do it right. Other opp is take your drive belt off and give the water pump pully A wiggle up down and in out, If you can hear or feel it knocking around then its buggered! Do some hunting around and change your thermostat and radiator cap, Make sure you bleed it properly after, Take your time Get it Hot and heater on.
Other poses.... Heater Tap leaking, check inside the car under dash and under floor carpet.
O-ring on steel tube that goes behind/under alternator into the intake under the therostat
Hose clamps on the join in the heater hose, Some models have this join.
Do a compreson test, Oil smoke when reving out under load, rings could be buggered from heat
check oil level, is it rising as you loose water
All these things went wrong for me after Cooking my last motor, Good luck.
To clean the heads and block I used a paint scraper and a FINE big (300mm plus) square file, Clean all the crap out of the bore when you done then check the bore for scaring and if theres a bad lip at the top ( The place the piston rings reach to at the top of each stroke).