Nice cascade .

BUT IMO R410a isn't good for 1st stage, You got 17bara unloaded (I know it's 25C ambient but still pressure is high), with load it'll be over 20 bara IMO so too much . R404a or R507 is good choose.

Compressors are STRONG so it should be good unit .

R1150 on 2nd stage?

And what has been the deepest vaccum You have been able to pull (reading from VG64) ??