I guess Im the odd man out here.... I say do the way you want to do it the first time... If you start making comprises with your dream build your not going to be happy in the end...
Alot is going to depend on your donar, as in my case I had 3 Fieros to use and all had v6's in them. I wasnt about to use a drivetrain that I had no history on. And personally my dream isnt to have a 150hp kit/replica.
Im proof of that, I orginally installed a sbc in my build. Although it ran great, the trans was always going to be the weak link. Two years later, I swapped in a LS4/4T65ehd. In my opinion its better than the sbc, but the sbc was way better than a stock Fiero V6. Point is I had to redo (spend more money) alot of things that I wouldnt have to if I had done the LS4 first.
Same goes for body work and paint, I got in a hurry and made a choice to not do what I had wanted in the begining. Now the car is down again getting completly sanded down and repainted. I recommend spend the money on your drivetrain and paint/body work, tires/wheels, the right way at the begining of your build. Things like brake upgrades, audio, interior upgrades can be done later....