Subframe buildup question

[srh3trinity]

I am finally at a point where I will have some time and space to do a little wrenching. I have enjoyed living vicariously through the board members in the mean time. I am going to be buying an early 2nd gen Firebird or Camaro eventually.
I have recently thought about the prospect of building up a Subframe and doing an LSX swap while looking for the right car. For those of you who have built up subframes, is this a viable way to go? I know it is unconventional, but I would buy an aftermarket subframe and add the components that I want and those that are proven along with the engine swap and after completing it, buy the car, install the subframe and then start working on the rear suspension. I realize that there are likely fitment issues with all subframe swaps, but this would be a reality at any stage in the game with an aftermarket piece, correct? Please weigh in. Thanks in advance.