Shall I use K&W Block sealer for Blown Head Gasket??
K&W is a good product... follow the directions to a T and you may be surprised. I've had good luck with it several times.
The key is to use it with clean water and drain the system and allow it to sit overnight before you refill the system.
It worked on my 78 Nova with a 305. I blew the head gasket when I started experimenting with timing and carburator tuning. I had my timing too advanced and I leaned out the primary jets. On. A hot AZ day I smashed the throttle and only heard "Nickels in a can" and I blew the head gasket. I was loosing about a gallon of coolant a week.
Its been about a year and still holding up to abuse. Just make sure you flush the system before using it and follow the instructions.