well I'm no guru but i have had experience in this area.
I put the exact rockers on my car with about 100k on the clock and never took the RPM's up high enough to get the valve float but after I swapped to a T-5 I started noticing it at about 5400 and higher. It felt just like you say, its like it hits the rev limiter.
I got a set of dual comp cams springs from summit for like $70, put them in and the problem was gone. It pulled much harder up top and could actually reach the real rev limiter
get some good springs and you'll be set
hope this helps,
-Drew