A quick look at Kubota's web site, show a 24hp engine is 19.6" long and weighs 205 lbs.
Kubota Engine America - Compact Diesel Engines
As far as speed goes, I think you just need to put the right transmission in it. I remember reading a while ago about someone putting a kubota tractor engine in a Ford Ranger and it worked fine. I think it was on the Cummins 4bt website. This isn't the one I was think of but it's one--
http://www.4btswaps.com/forum/showth...2203-gt-Ranger