RCU Forums - HBK2 and Belt CP questions

I am kinda new to the hobby and the forum and was hoping to get a few opinions to help me out. I been practicing on a sim I bought awhile back and recently got a couple real good deals on 2 slightly used helis on eBay. One is a HBK2 and the other a Belt CP. Both were flown once, crashed and given up on. HBK2 needs blades, flybar and a washout assembly. Didn't get the Belt CP yet. After reading a lot of the threads on here I think I will get a brushless motor and esc for the King 2 and I also read that the esc on the Belt CP seems to be inadaquate for the heli. OK, so here are my questions. Would the esc from the Belt CP be ok to use in the King 2 and just add a brushless motor , then get a better esc for the Belt CP? If so, what would be the best motor to get , a 3100kv or a 3900kv and what would be the big difference in the two on the King 2? Also the seller included with the King 2 a new Esky HH gyro. Not sure what comes on the Belt CP, but which heli would benefit the most from adding the HH gyro? Also, what would be a good esc to put in the Belt CP? I bought a new Blackhawk 450 SE from KaPlanes this summer, but it looks so nice sittin on the dining room table that I hate to take it out and crash it , so I figured that I wouldn't feel so bad crashin the less expensive ones for awhile first while I am learning. Any help or suggestions would be appreciated. Since I need to order some repair parts from Ushobbysupply to fix them anyhow ( I like to share the wealth ) I can just go ahead and order a motor and esc too. Thanks for any help. Oh yeah, and the King 2 also came with the 43 tooth belt upgrade in the box, and I only paid $60.00 for all of it. Seemed like a good deal to me anyhow.