I'm running a 2010 150 ETEC on my 1970 20SC and while the transom is fine, the engine is mounted on a Porta-Bracket - which I love and hate at the same time. The engine is great. The boat sits a little stern heavy so I have plugs in my scupper drains and pull them - if needed - when I run. Otherwise I get some water coming in when 2 of us are at the stern. That Porta-bracket allows me to idle in some really shallow water, and with my trolling motor on the bow, I have an offshore/flats boat combo of sorts!