Hi Ash - I don't know about motors , and you will get great advice from this site and from
www.rcgroups.com/forums if you care
to access that chat site - however since you are in the UK , and will probably be buying from a local source , do you know about
a wonderful site in your own country ? it's
www.modelboatmayhem.co.uk/forum/index.php? those guys are awesome , plus the site
will have ads and links to UK hobby shops .
wow - a 63" Riva ? could you post a picture ? it would be nice eye candy , plus any interior shots will help the guys advising you
on how to do a install - space requirements , etc. Good Luck !
Allan
Chicago