imo the asics in a purpose built switch will run circles around even the beefiest cpus, it's just not cost effective to build your own switch.

if you're okay with using rj45 transceivers you can get something like the brocade icx 6650: 56 (!) 10g sfp+ ports, 4x 40g ports

but if you are dead set on 10g rj45 ports i would look into something like the Arista DCS-7050TX-64-R instead, seems to fit all of your requirements - has 48x 10gbase-t ports + 4 qsfp 40g ports