1999 Chevy suburban LS 1500, change the ignition switch and housing won't stay r

Yes

Might as well contact locksmith .. Security system doesn’t recognize the new key .. Locksmith will know what to do .. Will have to ‘make a key’ that’s compatible.

Be sure to keep the ‘original’ (old) key for the locksmith to use to get the chip resistance reading from - so a working key can be made with same chip resistance reading - but using this new or non working key - as a pattern to cut by. Good luck!