4k 60Hz. 70 meters is enough.
Or, if it is not possible with Cat5-6 cable, or quality is compromised with compression - then optical extender.
Can i hope for 0 delay with this extenders?
What kind of latency can I expect in video transmission?
Latency is the measurable time that it takes a signal to get from one point to another. HDBaseT adds virtually no latency to the signal – less than 10 microseconds over 100m of cable.
(One microsecond (μs) equals to one millionth (1/1,000,000) of a second. One microsecond is to one second what one second is to 11.6 days.)