Ok, I've had quite a bit of expierence with the different 351's. First of all, let me say this.....STAY AWAY FROM THE 351-M!!!!! A friend of mine built one very stoutly, and it was a dog compared to a mildly built 351-W! As far as between the Windsor and Cleveland, what you have to determine is do you want much more power or much more available parts. The Windsor has many different parts available to it because Ford produced it for a very long time, and, quite frankly, it is a VERY strong and reliable small block. You could even easily (Compared to the Cleveland) go with Fuel Injection. I've heard, don't know for sure, but I've heard that if you place a 400-M Crank into a Windsor, all you have to do is alter the finring order and your little Windsor will have 400 cubes at its disposal. However, the Cleveland will produce LOTS more power, providing you can get a set of 4 barrel heads. My dad built a Cleveland using 4 barrel heads and put a mild cam and good aluminum intake on it and it SCREAMED !! It really had alot of power. If I had to choose, I would definitely go with the Cleveland. I'll have to be honest with you though, when I built a motor for my Thunderbird, I had a choice between a stroked 302, a 4 barrel 351 Cleveland, or.....the Mighty 460. I chose the 460 because its lower end is designed alot like a small block Ford with it's simple design (only much larger) but the upper end (mainly the heads) are designed with the Cleveland types of chambers which produce LOTS of power. Hope this helps.

TBirdGuy