410 LA small block will not rev past 6000

SpeedPro - HT2011R LIFTERS, Anti Pump-Up, before I went to a hydraulic roller I ran these on all my flat tappet builds, each time my foot was the rev-limiter!

Setting these up with 0 (ZERO) preload is the key - which is what they are meant to do.
Yes Yes, adjustable rockers, Isky prefered, zero lash (pushrod stops turning) Crane anti pump up lifters. I was going 118, 4.88 gear and 29.5 slicks 6800