1988 Toyota Pickup engine malfunction

About two years ago I purchased a long block engine from a machine shop in MD. All the seals on the engine were put on by the shop except the water pump and the intake maifold. The engine was bored over 20. The engine was suspose to have a 3 year or 36,000 mile warranty. The engine showed up at my door step out of correct timing. I replaced all of the parts requested and began putting the engine back together. I could not get the timing correct because of the fact that the long block that was sent to me was put together incorrectly and was off one tooth on the chain. This took me about thirty mins to diagnose because I had figured the erro was some how on my part. I took the truck to a near by ase certifed shop where the erro was corrected. The new Less than two years later and less than 5000 miles on the engine has been put on it and engine seized up on me on the freeway last friday. I have a after market pressure sensor. The pressure spiked above 60 psi 2 mins before it began dropping drasticly. I noticed the oe oil light flickering I pulled over to see what had gone wrong. The truck lost all power and I placed the vehicle in nuetral and coasted to a stop. Oil was dripping from the front main seal, the head gasket, and what I am guessing is a leak in the oil pan also. I found extremely small flakes of metal in the oil dripping from the pan. The water tempature did not reach the red zone but it did get extremely high. The radiator fluid level never changed. I checked the oil filter and pressure sending unit for leaks and found none. I fail to see how the engines malfunction is my fault but the builder of the engine insists it is. Do you think the malfunctions in the gaskets and seals could have been caused by abnormal combustion in the oil pan area causeing extreme pressure? Could the malfunctions be caused from the incorrect timing issue the shop caused in the first place? Do you think I am responsible for another engine or is the machine shop?