Personally I would not go less than a 351. You can go Cleveland or Windsor. The Windsor parts are a little easier to come by than the Cleveland. Watch out or you can get yourself caught up in a heated debate about these two engines. Truth is the Cleveland has a bit more torque.
A great source for engines that may be close to you is the Engine Factory located in NJ. Check out thier website at
www.enginefactory.com
I purchased a 351W crate engine from them a year ago and I can honestly say it has performed flawlessly for 2000 miles, so far. I have gotten on it hard quite a few times.
I decided to go with an Edlebrock Performer RPM manifold, Holley 700 CFM four bbl carb w/vacuum secondaries ( you can go double pumper as well ) and an MSD 6A ignition with the MSD billet distributor. The heads are World Products cast iron. Nice heads even though they're cast. The Engine Factory is now using Edlebrock Aluminum heads almost exclusively. They use a high output cam but they don’t specify the manufacturer. As far as a transmission, I have the new Ford super-duty 5 speed T5. I have been told that this is probably my weakest link. I know these trannys are rated at 330ft-lbs torque, so if you go with a stroked or higher performance rig than you should consider a 3550 or a Richmond. With the T5 I run a 3.5 rear and I have no problem smokin' them in 3 gears (if I really want to). In 5th gear at 70mph, the revs will drop to about 2K.