Hi Hans;
I had good luck with rcv91cd
One of the distributors is WestonUK
they are very good (I had personal experience with them) in terms of customer care and carry a whole line of the rcv engines.
If you need more info just give them a call.
here is their web site address:
[link=http://www.westonuk.co.uk/westonuk2_036.htm]WestonUK[/link]
I also have a 4* 60 and planning to put rcv91cd in it.
Happy landings,
ustas