426 stroker, is it reliable?

It's not a definate that it will need anything, but you have to be aware that you are sacrificing something to get more of something else. The factory had to make them last with the knowledge of the day... To get more power, you acrifice longevity. I have friends with 40K miles on 4.15 stroke RBs, and another with less than 10 on his 4" LA and it's got with ring seal issues. (I had nothing to do with either one... Just stating examples) The guys that do a lot of them and have a good understanding of how everything interacts will know how to get the best life reliably. That same group will not be the cheapest in parts or labor becasue of that. Regardless of stroke or rod/stroke ratio, the taller the piston, the better the longevity because the ring sealing will always be the first to show signs of wear as the piston rocks at TDC.