Absolutely. You are, however, completely wasting time and effort. This is very deep into the "don't bother" territory of RB engine work. Whilst, if you you are accustomed to the complete absence of any torque or power than an RB20E is able to produce, an RB20DET might feel fast, it will, in reality, be a horribly slow and compromised engine into which you have poured far to much time, money and effort in order to achieve an underwhelming result. That same time, money and effort could be put into dropping an RB25DET in. Or, you could even put in an RB30E+T.
But, assuming you are not discouraged.....this is not a new idea, has been bashed around on the 'net and done a gazzillion times before. So, if you search, you will find.