No start

Is the valve and ignition timing correct? If so Do below to determine if its fuel or spark issue

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine at least 3/16 away from ground -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if so, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, coil's resistances, distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it

1st off, who replaced the head gaskets and how soon after that did this problem crop up? If a shop did it and it was immediate, take it back and tell them to fix it under warranty.

If you or a friend did it, time to troubleshoot.
Timing. Make sure the distributor is in right and not 180 out. Make sure it is set properly.
Make sure the timing chain hasn't slipped or skipped teeth.
Remove the distributor cap and make sure the rotor turns when the engine is cranked over. If not, see if it turns by hand. If so, replace it. If the rotor doesn't turn at all, there's a problem with either a broken camshaft (Not likely) or a broken chain or timing gear.

Check for fuel pressure and delivery.

Check for proper spark to the plugs. If not there, trace it back to the coil (packs), ignition module, etc.

Check the air gap on the cam and crank sensors. These are usually set incorrectly.