hmm, something just doesnt seem kosher, something is the wrong size, i havent ever had this much trouble, even with putting the valve springs back on it shouldnt take more than about 2 hours. the first time i did it i used a shitty valve spring compressor and still didnt have as much trouble. i hope you get it figured out, im sure its something simple. but on a serious note, if you have the head off of the engine (or even if you dont) you should really really really clean it up alot more, even if you used a couple of cans of brake clean and an air compressor, i see alot of tiny particles on there and can you imagine what that is going to do to your main and rod bearings? heck some of them look big enough to score the cylinder walls. good luck man