Dont go with the 429 its so heavy and parts are expensive and hard to find.
The 351W makes an awsome small block for several reasons. Parts are easy to find as its in the same family as the 289-302 motors. A fresh 351w with a nice set of heads should put you in the 400-450hp range and still be 100% streetable. If its cubes that you want, the 351 can be stroked to 427ci, with 1/2 the weight of bigblock. Also all the small block aftermarket heads like AFR,DART,EDLEBROCK,TFS will bolt on a 351w. The 351w probably has the most potential as far as cost to hp out of all the ford motors. If your looking to do a cheaper build-up you can buy a 393 stroke crank from scat for about 350$ which uses stock 351rods and 302 pistons. Alot of options with this motor, you cant go wrong with the windsor motor.