It is a HUGE task and really not worth $450 , I have a TL-922A and use it as is , works flawless. I did the mods on 3 or 4 of them and really , there is no benifit unless you are a knit-picker and everything needs to be perfect as well as micro analyzed by a ham guy with a doctrate in RF Engineering telling you everything he would do to make it better...
Use it as is...
Here there are if you want them (google is wonderfull)
http://pa0fri.home.xs4all.nl/Lineairs/TL922/tl-922eng.htm