Hi Carlo,
Look ASTM A 958, you can find mechanical propierties for 1020, 1025, 1030, ......4130, 4140, .....8625 and 8630. But, It`s good question, why you compare CF8M whit 4130?.
Anyway, if you need mechanical propierties of 4130 Q & T, what it`s the HB?, On it depends all.