the engineers cert doesnt mean u cant drive the car, its the modifications that mean u cant drive it, tho there are alot of p platers ettin round with e conversions that dont et bothered.
if u can et a pinkslip for it on the dodge u wont need an engineers, most workshops probably wouldn't even realise that the motors been chaned, usually as long as a car has good brakes tyres and suspension, and nothin major is wrong with it, u wont have an issue