I can see some possible issues with that:

1) Even though the dimensions might be right in terms of length, width, wheelbase etc. The mounting pattern might be for old school trucks which will severely limit what you can use for trucks.

2) The concave might be uncomfortable. A concave that feels good on an 8" board might feel a little steep on a 7.3".

3) Time and effort. You know the old saying, "Time is money." How much effort do you want to put into it and how much payoff do you think you will get from it?

IMHO it would be wiser to spring the $30ish on a brand new Decomposed from eBay.