MDS is a good engine and are VERY good with a pipe .
And those prices you see ARE good and the seller IS reputable . I personally bought three engines from him and without a single problem .
( ps ... the engines might be your top shelf , BUT ... are a LOT faster than K&B's ) )

MDS Engines
4105 Fieldstone Road
Champaign, IL 61822
Phone: 217/355-9511
Web Site: http://www.mdsengines.com