If you want to get into road racing you might want to consider putting the stock motor
in, run it N/A according to the IT rules. You will fall into ITS class. It is a pretty good class to be in. We used to run a BMW 325is in that class and competed very well. I know a guy with a 240 and his car is capable of top 10's or even 5's. The class is usually dominated by the second gen rx7's.

If you do decide to run with the turbo and in the SPO class you need to understand that alot of the cars in that class and the other classes in that group (GT1, ect..) have alot of money in their cars and might not be too kind to rookie inexperienced drivers.

I was building a 94 bmw 325 to run in ITS class myself but after the rule changes requiring that car run a restrictor plate I decided to go back to my partially built CRX and run in SPU. Fortunately that class does not run with the GT1 group. I am however still having second thoughts about not starting out in one of the IT classes first.