This is starting to sound strange. What exactly did you mean when you said a stone blocked the engine?
If you didnt tighten the head back down propperly that could be a huge air leak also. To tighten the head screw in all the screws just finger tight then snug them down equily in a criss cross pattern & just a hair more than what most people consider snug,like 1/8 a turn after finger tight.
The part that scares me now is you say the glow plug is hitting the cyl? Do you mean hitting the piston? You didnt leave any big round shims off the top of the eng when you put it back together did you?
If the piston is hitting the glow plug then its a simple fix.Just take the motor out of the truck,throw eng in trash & install new motor & that will fix the problem guaranteed. This time put a zip tie around the air filter to keep it on the carb.
Good luck