A CT20 will not be fine...it will be shit. Have a look at them. The comp wheel is tiny and a totally antiquated design. It has crap efficiency (heats the air badly) and for it's size has more lag than any turbo i've seen. The wastegate port is tiny so high exhaust backpressure is guaranteed. On a 3TGTE they were only just adequate and even there i reckon they were crap. On a 2 litre with that great yamaha 18RG head a CT20 will not give anywhere near the result of all the other options you have been presented with.
The CT20B is a twin entry turbine but doesn't have any model designation on it. Dead easy to pick. The only other twin entry turbine turbo Toyo do is the CT26 and that has CT26 stamped on the comp housing.