Ok, for starters, you don't need to change the motor mounts. You can use the stock 5.0 mounts on the 351. You will need a different oil pan. The 351 is wider and the 302 pan won't fit. You need to find a double-sump 351W pan. Also you need a different intake manifold. You can bolt your 302 headers onto the 351, but you won't be able to bolt them to the rest of the exhaust. You will likely have problems with hood clearance and if you keep it fuel injected, you might have to clearance the cowl panel too. The 351 uses a different distributer, so if you want to use your stock ignition system, you need to make sure it is the right distributer, or get the right one if it isn't. The motor can be swapped in, but it isn't just going to drop in place of the 5.0. If you don't have the money to rebuild the 5.0 right now, then you probably don't have the money to swap in a 351 right now. If I were in your shoes, I would buy the 351 for $100, and take it completely apart and start rebuilding that. If you have never rebuilt an engine before, then this will be a good learning experience, and by leaving your 5.0 in the car, you can still drive it while you slowly collect parts for the 351 rebuild. You could even get a stroker kit for the 351 if you want, and there would be no reason to rush in the build. This way when you are finally done building the motor and collecting all the necessary parts, you can swap it in one weekend and not be out a car for too long.
Mike
