26 inch wheels and fork on a 27.5+ frame I have a 26 inch bike(Specialized Rockhopper 2007) with decent wheels and fork. I want a more slacker head tube and better geometry than what i have now. I might be interested in one of Ragley Marley, Ragley Piglet Ragley Bluepig frames. My fork is not tapered. I know there are some conversion rings for that. I wanted to know if i can transfer all parts from the present bike to this new frame. I am little bit apprehensive about quick releases. I heard some frames take thicker quick release rods.
Overall its probably cheaper and certainly easier to sell the bike you have and buy the one you want. Building a bike from a 27.5 frame with 26 components you may end up with a bike geometry that is 'out' and handles worse than you already have. 

The new frame is likely a though axle, and may have a wider (Boost) spacing, meaning the rear hub will need adapters or replacing. The bottom bracket and seat post are unlikely to be compatible. You may need a new chain as the chain stay length could be longer.