usually I don't like to get in the middle of these things, and I have only been working on boats about 5 years, but most marine engines are standard rotation just like a car, but a few rotate opposite. I haven't ran across one yet but it seems like the most common application is twin engine boats, but have been told that once in a while someone will decide to put a reverse rotation in a single engine boat.
Okay I have been reading some of these and let me start off by saying this the saying that the 4.3 is just like a 350 just minus a couple cylinders you are so wrong about the only thing that is the same is the bore diameter of 4.00 in the rods themselves are acutually offset you can use standard sbc rods but you have to have them machinedthe 4.3 is very expensive to build in comparison the distributor yes you can use a v8 but you will have a slight miss in it since it will be picking up on two extra cylinders don't cheap out go online and buy a v6 hei edlbrock sells a nice intake for them for about 275 bucks you also have to watch out for your block you could get one with a balance shaft or one without my first one didn't have one and it was out of a 90 Chevy 1500 2wd truck so there is a lot of research you will have to do on your block casting number also the 4.3 is a even fire motor you can buy a crank to change that but they are very pricey
I've got a 4.3 in a 2004 s10. Will I have to buy another intake to carb it or can I modify the stock one? I'd rather run this than rebuild a 250 straight 6 for it as long as I can carb it and get a turbo 350 or 400 to bolt up