Replacing my old guages with I-Command-How much can i do.

I have a 2007 225HO on my 2000 522 Ranger.
I currently have a NMEA 2000 on my boat with the following inst. hooked to it.
225 HO Etech
Low 113C
Low 520C
Low. GPS ant.
3.5 I-Command
WP sensor device for 225HO
2' I-command.

My boat still has the original controls and the original speedo and Engine check Tack. I am wanting to replace the Speedo and the enginecheck tack(off of 2000 225 Ficht) with 2- 3.5 I command Guages. Is there any problems with my NMEA 2000 handeling all of this and what will happen when i disconnect the enginecheck tack.