[THEFERMANATOR]

I have no affiliation or 1st hand experience with any of these remanufacturers, just some I found in a google search. Or you can normally pick up complete running engines for under $500 off of craigslist. I wouldn't go with a V8 myself, too much weight, a gear change will most likely be needed in your outdrive, completely new engine bed, new mounts, most people agree the added power is a waste as you will rarely ever be able to use it, and the cost. Mercury reccomended the 4.3l V6 to replace the 3.7l 4 cylinder.

http://www.michiganmotorz.com/37l470...ww0aAjgM8P8HAQ
http://m.ebay.com/itm/470-MERCRUISER...-/171828567100
https://www.perfprotech.com/first-ma...product/245003
http://bpi.ebasicpower.com/shop/inde...=406_1733_1734