3.8 or 305 ?

Re: Stock. Not necessarily, but any mods or bolt-ons will need a CARB EO#. Definitely on the "not approved" list are cams. But as long as it passes the sniffer test, and it doesn't idle like a top fuel dragster, nobody will really know. Kind of a gamble.

I did a 305 swap inmy Regal including all of the CCC system. Also swapped in a 200-4r that came with the 305. Also 305s are far better than the n/a 3.8s which are at the bottom of the barrel. Up till 10 years ago the aftermarket used to make lots of smog legal performance parts. Sadly most are long discontinued. Crane used to make smog legal cams which I have in my 305. Edelbrock and Hooker used to make smog legal headers. GM even used to sell dual snorkal aircleaners and performance computer chips.

I'm in the process of doing that same swap on my 82 Bonneville . It had a 3.8 and I'm putting a 305 in it.
I have a good spare 3.8 but I want a little more power. Obviously it's a lot less work to just swap engines but
the 3.8's have so much garbage on them and are harder to work on. Although there is a lot more room in the front,
the 3.8 is really tight on the inner fenders especially the passenger side. I feel a SBC fits in there nicely and is simply easier to work on..
timo22

For $400, I'd be wary of the "recently rebuilt" part.