My $0.02, and it probably isn't worth that.
Build the engine you want now, build it right the first time, and be done with it. I understand the funds may not be there, or other complications may arise. However, find a way to make it happen. The older I get, the more of a rip the band-aid off now type of person I have become. You just don't know what monkey wrenches are going to be thrown into your best laid plans next week, month, year. Plus, unless the Fed throws us into a deflationary spiral, ala Japan in the 90's, it will only cost more and more to build the motor you want now, later on down the line.