One place is CP:
http://www.cpperformance.com/images/620/620-1000.JPG
"This race-designed kit is the ultimate in engine mounting. Super strength 6061-T6 aluminum plate mounts. Competition proven performance, ideal for high performance ski boats. Highly polished and comes with polished mounting feet. These are semi-custom designed to your boat. Available in anodized and coated finishes. Please call for applications. Final fitting is customers responsibility."
http://www.cpperformance.com/
LO