I've found the RA-Tech nozzle and barrel to be good investments. The barrel have great accuracy and the nozzle has lasted 6 years now. The RA-Tech bolt unfortunately was way off spec and needed a fair amount of material sanding off the receiver to get it to cycle smoothly.
Mapleleaf buckings are great with the metal c ring which helps seal and grip the nozzle. I chose 60d for 450 fps, if you are running it sub 350 the 70d will most likely be too hard, 50d will probably perform better.
I would recommend getting a proper scope that is rated to recoil, Mine destroyed 2 scopes before I switched to a vortex.