I have a Mercruiser 160 I-6. I have access to a free marine 305 Chevy from an OMC app. Mounting the engine is not a problem. My problem is the wife, who MUST be kept happy, will not tolerate thru transom exhaust. My boat,'78 Silverline, came with a 470 Merc and I swapped in the 160 Merc. Had to...