first suggestion: STOP TYPING IN ALL CAPITAL LETTERS
The mag brake out of your other CZ-75's will fit in the SP-01, if you wish to shoot it instead of the other CZ's.
The upgrades I would personally give it:
triggerjob so SA pull is about 1kg
better sights
I don't know what holsters are legal in Modified division, we don't shoot that in USPSA, it's only in IPSC. I personally use a CR-Speed in Limited, but it's definately more than $8 USD.