FAR AIM has some information on this recommending 10 hours for a complex conversion. The 10 hours is not mandatory but most clubs in the US are very anal about it. A twin rating in the states is 10 hours as well.
I did a couple of hours to convert to an arrow in the UK then did about 20 hours flying it around. When I wanted to get a conversion to a US complex rating I got a friendly FAA instructor in the UK to do a currnecy check and he then signed off my BFR and the complex rating. This signoff has held me in good stead for several years.
The arrow is not that big a deal. The floppy prop is more difficult to understand than the u/c lever but a couple-3 hours should do it.
Then all you have to look forward to is the inevitable wheels up landing we are all destined to make.
Good luck.