Rakza Z is cca 48-49, so even H39 (cca 51) might feel a bit harder. I'd start with that if you like the RZ's hardness... So I recommend that, but taking H40 would not be a catastrophy ;-)
I like FTL (Falco Tempo Long), it's less slimmy ;-) Actually imo, it doesn't matter that much... I use 1...