Im not sure what the GSR goes for, but try calling around to the junk yards and ask for a price on 1 and how many miles it has on it to get a ball park figure. I bought my Ls B18B1 for $700, so I would guess maybe around $1500? ? ?

As far as the Catalytic converter, if it is bad you will have to replace it or the CEL will still be on when you replace the engine. . .

I would post it together, but as willing to part out, you may get more for it parting it out, but may be stuck with the left over parts that no one wanted. . .

You could also see if the place that will put in the new engine will take the old one as a trade to knock off some of the price, that way you don't have to worry about it. . .

Let me know what you end up doing. . . I got 2 B18B1 engines but thinking about selling them and going GSR. . .