are parts sold by stangparts.com reliable because i saw a engine for 350 and it seems pretty cheap

 

They sell used parts they pull off of wrecked Mustangs, so just know that the parts are used. They do have a good reputation for having a big selection of used parts and have been featured in Muscle Mustangs and Fast Fords magazine but I have no personal experience with them however. You might want to check on a local salvage yard near your home first to see what they have available in the way of used motors as often they can let you see and hear it run before you buy it. A good yard will offer some type of warranty also for like 30-90 days so be sure to ask about this too.