If you want to build a LS1 for your car, trying to rip one out of a vette, or F-body might cost a lot because of what it came out of ("that be a vette motor boy") No, all you need to get the expensive part is find any GM with a Gen III SBC, which is what the LS series engine is. All 97+ Vettes, 98+ F-bodies, 99+ Silverado series pickups. There are several, the 4.8, 5.3, 5.7, and 6.0. The '01+ 6.0 is a real good bargain because they had aluminum heads that flow similar to the LS6 heads, pre '01 many had iron heads. The truck intake flows like the LS6 also, the reason there is a difference between the truck and car intakes is because the truck intake would not fit under the hood of a F-body or Vette, but it would work great under a cowl hood of a Mustang.
Me Three. They all have potential, the advantage with the LS1 is the fact from the factory it's already pretty stout, the ford motor is going to need some work. If your starting from scratch, it's a toss up for the most part. Parts for the 351 will be cheaper. The only real advatages the LS1 motor has is the aluminum block, which you could get from dart for the ford, and the reverse flow cooling system where you could run more compression, the rest is all in how it is built.
I did, but I ain't givin up my 5.0. My truck has a LS1 in it, but it has a steel block, less bore and stoke, but I'll tell you it moves the truck. While most truck motors tend to fall off after 4000rmp, my truck's motor starts pulling harder but the tranny shifts at 5300 and I wish it would stay in gear longer because it just contiues pulling harder. Mine is only the 4.8, but in a regular cab short bed. I have read they run mid-low 15's bone stock with that confuguration, the 5.3 runs high 14's stock.