The down side is that the car will have less value when you decide to sell it, which you will someday. Use a car that has appeal so that you dont dump money down the toilet. Some people use the family car because it needs a new motor. Big mistake. Make sure its a car that would sell easily and for $$$ if it still had a ICE in it.My first build had a salvage title. Depends upon the condition. Flood damage needs to be replaced and if there is rust starting it needs to be stopped before it eats the car up. Other wise if it's in decent enough condition sure. Is it something YOU WANT to drive all the time? If not or if there is any question about that then the answer is NO. Don't do a build unless it's a car you really want as a daily driver. If it is not then don't convert it. If your doing this car because you have it but don't really want it then don't. Only do a car you WANT. Treat it as a long term investment too.