Altough you can input 255 lines as the maximum for line sync this is not true
At lpb 8 and 110 bpm , delay set to 128 , it will atually repeat at line 72.
Yes, the maximum delay size is 5000.00 ms. Depending on the current tempo and LPB this can be less than 255 lines. The delay needs some fixed maximum delay line size to avoid reallocating them on tempo/LPB changes.