I couldn't say anything as far as frame data but I don know that when senaru plays he always "ends" his blockstrings with either 2A, 5A, or 22 gunshot series. 5B is also extremely good for pressure since it is a standing low and you can always reverse beat into an A normal. My biggest advice with blockstrings would just be to always let yourself have an A normal to reverse beat into. So if you start your string with 5A avoid going 5A>2A or vice versa since remember its only 1 normal use per string.