There's no "head warpage" sensor on any type of vehicle I've ever come across. You can only do a compression test, if it passes that's not the problem. If not then a cylinder leak down test will tell you what's dead.
As far a timing belt letting go, your engine would sound very different when trying to start since the valve train would not be spinning and only the crank would spin smacking the pistons into the valves and bending stuff.
The issue COULD just be the head gasket itself, however you'll still want to have the head checked and straightened in you can find a good machine shop (provided the engine doesn't pass a compression and/or CLT test).
It's possible there could have been some damage to the crank sensor on the front of the engine, but that's kind of rare.
As far as BIG money for an engine, if you're pretty mechanically inclined you can always wedge a 350 with a turbo 400 in it for less, although you'll have guys SCREAMING scaraledge. Kind of ruins the handling a bit but man they go fast in a straight line.........provided you can keep the wheels on the ground. If you do go that way, make sure you go all the way with a hole in the hood and a bird catcher sticking through it. ;-)
Best bet, pull the belts, check ALL the pulleys. Look for anything rubbing on the drives. Do a compression test and then go from there. Other than that there really isn't any "secret knowledge" I can impart to fix your problem.