Bill,
Seems that you've already decided on SPF. I think you'll find it to be a well-made car, strong enough to handle virtually any engine combination you want to install, with good creature comforts and amenities (relative to a skateboard or most other Cobras, anyway), with very good dealer support and tech help available. Seriously, my car is comfortable enough for me to drive for two hours or longer at a time and, with the top up, is cosy inside down into the 30's and plenty roomy and I'm 6'6" tall. One of the great things about SPF, and why they appeal to such a wide range of owners, is that any Ford V-8 is "right" in a SPF.
Some guys install FE motors and, if you want the coolest looking, coolest sounding motor, the FE wins, hands down. It's also the most expensive way to go.
If you want the absolute rompin'est, stompin'est, drag racin'est, gas guzzlin'est, most intimidating, window-rattling, alarm-setting-off, dog- and old lady-scaring, Corvette- and Viper-thrashing Hell-child in the parking lot, the big block is the way to go, but you probably won't want to take many trips in it.
If you want a scary fast, fun to drive, chick-magnetic, daily driveable sports car that will be fun on trips, get 12-15 mpg on pump gas and not make you go completely deaf or pi$$ off the neighbors too badly (assuming you live in a neighborhood-I don't
), talk to one of the engine builders who advertise here on CC about a Windsor-based motor in the 400-500 HP range. I agree with Trularin: Don't try to tell the guy how to build your motor but do tell him what you want to do with it. If you want, or don't mind a lumpy idle, tell him. If you want to be able to idle through town without going "Rumpity Rumpity", tell him that. If you're concerned about gas quality, discuss lowering the compression a bit. If you want to just go fast and are willing to put up with a little inconvenience, discuss that with him, too. Look at the Ford crate motor as a kind of benchmark. It's relatively cheap, reliable and powerful, but you can improve upon it in all dimensions if you want to spend the money. If you don't want to spend more money, you can still build a very fast, very enjoyable car with a 385 HP Windsor.
Two further crumbs of humble advice:
1) Look at the used cars. There are a LOT of nice cars out there at reasonable prices, Eric Brown's (Great Asp) being one, but there are many others on Club Cobra and Cobra Country.
2) Plan to attend DVSF 4 if possible. It's only a month away and not too far from where you live. Even if you have your mind made up, a trip to "The Fling" may either convince you you're heading in the right direction or possibly save you from making a mistake.
Good luck,
Lowell