Looking to put 2 speakers in place of my speedo / tach gauges. I moved them to my bars so now I have 2 empty holes. Ive seen it done somewhere but I have no idea which size fits , brand ect. fitting the grilles isn't necessary either. also i have a JM rocker 4 channel 500 watt amp. have stock location front speakers and lower fairing speakers. will I be able to add/ splice off this current system?