Wow. I am really surprised. I had similar total hours when I did my FAA SE IR and then came back and converted. I did also do my ME rating in the USA, bare bones though, literally minimum hours and test. When I converted I only did c15 hours total, including the test (got dispensation from CAA for the hours).
Not sure where you trained, but I trained in southern California and we did cover all those things that you didn't.
NDBs - I was taught about NDBs (although admittedly there is a huge lack of NDBs in the USA)
Holds - I was taught about gates and abeams and we practiced alot of holds, including at airports and on airways (cross radials).
Comms - I found it much the same
Uncontrolled airspace - we did train at uncontrolled airports and also I had experience of the "remain outside controlled airspace" calls.
I did do my course quite intensively in the USA, completed the 40 hours and test in 15 days. I was also very pro-active with my studying, including sitting in the back with other students and practising on the sim if I was confused with anything. Also had very good ground briefings. And the King videos!!!
So it can be done, I guess it varies depending on the person.