1995 GMC Sierra overheating

I have a 95 GMC Z71 that I've had for 18 years so it's very sentimental to me. From just driving it you wouldn't believe it has that many miles on it how smooth it runs. At the beginning of winter I replaced the radiator since it had a slow leak and was having to add water to it every other week. After I put the new radiator in, the return hose coming off the heater core I guess the hose clamp I was using either galded up or I just didn't have it tightened enough. After watching my temp gauge, showing what I was expecting it to show I stopped watching it. The next day while I was driving it I could tell something was wrong and I looked at my gauge and it was pegged past 260. After it cooled and noticed there was nothing in the radiator I filled it back up and noticed where the leak was there at the hose coming off the heater core. After fixing where the leak was it was still overheating to where it was pushing all the antifreeze out of the overflow reservoir and the main hose going to the thermostat was as tight as a banjo string. At first I was thinking it was a bad thermostat until I replaced it and did the same thing. I even manually placed the thermostat into boiling water to visually see it open. It turned out that there is a crack somewhere in my cooling system but not going into my oil. I took it to another shop and they said they took the thermostat housing off and noticed some bubbles coming up. He said it wasn't much but enough to cause the problems I'm having. You can even see the excess steam building up when I take my foot off the gas while I'm slowing down toward a red light or stop sign. The truck has too many miles for me to start talking that type of surgery I guess. I really don't know what to do. I went and talked to another person that has his own shop and told me a way I might be able to fix it, for how long he couldn't say. He said it could be 2 months or 2 years he couldn't say for sure. He told me to rent a radiator compression checker and get a bottle of Blue Devil Head Gasket Sealer. The way he told me to do it was different than the bottle says but made sense what he told me. He told me 1st to take out all the spark plugs and then pressurize the radiator. After doing that have someone spin the engine over while observing which cylinder or cylinders has the leak by watching all the fluids shoot out those cylinders. And after that put the spark plugs back into the good holes. Once you've done that and the cooling system is completely cleaned out of all antifreeze to pour the bottle of blue devil in to finish filling the radiator. After cranking the engine he said the engine would run like crap and I'd have to keep the RPM's up so the engine wouldn't die out but eventually I would start seeing the fluids slowly start going away. After I got to this point just shut the engine off and wait till the following day and everything should be good to go. However, it never got to this point. After I pressurized the radiator to 25 lbs, we spun the engine over for almost 30 seconds on 2 different occasions and never lost 1 lb. So I returned the blue devil and am at a stand still once again. I did replace the water pump the same time I replaced the radiator. The person I talked with at Advanced Auto where I returned the blue devil to said he would still run that blue devil through there that he still thinks that could fix it. My biggest concern is not being able to run it for the specified time of 50 minutes or so without it getting too hot causing me to kill the engine. Any advice would be hugely appreciated here since this truck is like my son lol. I really don't want to take this to a junk yard for peanuts if it can be saved. I have been unemployed with chronic back pain for over a year and a half now. If you can help me anyway with this I would happily give you a donation. I know you probably hear that a lot but if you can save me any money from a major garage bill I will gladly give you a donation.

Sincerely,
Mitchell DeVaughn
615-483-6071