I have a 87 caprice wagon with a 307. I want as most HP as possible but i want to keep everything original on top end like smog system, cruise control, intake, ccc carb, exaust manifolds, ect.

How much HP is possible?
403 or 350?
Is there any crate (rebuilt) one out there that are good?

 

First off, are you sure it is an Olds 307 and not a SBC 305? If so, that is a terrible platform for performance. I have had a bunch of Custom Cruisers, ran great, reliable, decent response, but you simply are not going to get much out of it. Best bet is to swap in a 403, very few will be able to tell the difference.

 

With that expectation, the 307 is out (providing it IS an Olds motor).
A 68-72 Olds 350 has been proven to work with the stock emission stuff and put out good power. A 403 should work but I do not know of any who ran it with the smog crap.

 

It almost certainly IS a 307 Olds, as most of the B-body wagons in the late 1980s got the Olds motor (as did my 86 Caprice wagon). Unfortunately, as others have noted, this is a horrible starting point. The 85-90 307s have tiny ports, large diameter roller lifters, and crappy intake and exhaust manifolds. Also, "smog legal" depends on where you live.

It pains me to say this, but about the only smog legal way to upgrade HP on this motor is to swap in a later model, smog legal LS-family drivetrain. You cannot legally bolt in a 455 Olds (since there is no version certified to meet 1987 model year emissions) but you CAN legally install a 2012 LS9 with 660 HP (or anything in between) if you choose - even in California - so long as you also transfer all the associated emissions equipment from the donor car.

 

The only things I do to my 307, is stuff that is going to be transfered to the 330

 

X2 for the 87 caprice wagon + LS9 ... Supercharged sleeper wagon!

 

The wagons got the 307, I had an 88 4 dr LS with the 305. Nice cars.

 

Yeah, and you too can buy a brand new LS9 in the crate with electronics for a mere $23,000. Add the correct trans, fuel system, mounts, and exhaust, and you can probably have all the parts on your doorstep for $30K.

That's only about ten times what one of these wagons is worth, of course.