Want more power out of my 86 estate 307!!

There are a few more questions you need to ask yourself.

1. How much more power do you want?

2. Are there vehicle emissions inspections where you register the car?

3. How much do you want to spend?

If the answer to the first question is "lots", and the answer to the last question is "as little as possible", then I would do as other posters have recommended and do an engine swap - assuming that's legal in your area.

If it were my car, I would be looking to get "moderate" power increases for as little money possible, and emissions aren't a concern in my area. I'd do the following, in order of bang-for-buck:

1. Small diameter, long-tube headers and dual 2" or 2-1/4", mandrel-bent exhaust with aftermarket mufflers. An X-crossover is nice if you can fit it but adds more cost. Sounds like you've got the exhaust system pretty much covered already, but if you don't have long-tube headers on the way make sure to get them. Long tubes will dramatically improve power across the whole power band. Don't get the tube diameter too big or you'll lose low end instead of gaining it, and that 307 won't make enough power to need big tubes anyway. 1.5" would be a good bet for header diameter, or maybe 1-3/8" if you can find them. Shorties won't improve low end very much, and you'll need all the torque you can get out of the little engine in your big car. You've already spent the money on exhaust, so if you don't have headers on the way budget another $125-$250 for them. Make sure to use quality gaskets and loctite the bolts so they won't leak! Also make sure to gasket match the headers to the heads.

2. Open element air cleaner. The factory air cleaner is probably a restriction even to the stock engine; with the new breathing of your exhaust your air cleaner will almost certainly be a restriction. Sounds like you have that on the way too.

3. Toss the carb and intake manifold and put on some non-emissions units. Either find a factory setup or Edelbrock or Weiand or Offy probably make a good dual-plane intake that will fit your engine, again don't go wild here. Same thing for the carb, get a small 4-barrel, either a Carter or Edelbrock (which is just a re-badged Carter anyway). 500cfm is plenty big for the power your engine could make, and putting too much carb on your engine will make drivability suffer. Make sure to gasket match the intake to the heads.

4. If, after putting the previous mods on the engine, you still want more power, the next thing to do is a cam swap. This involves more work and $$ but if done properly can really wake up the car. The cam in that engine is smog-friendly (read: gutless POS). It was previously stated that your engine is equipped with a roller cam; rollers are great because you can have your cake and eat it too, i.e. fast valve lift rates and low friction. I'd send my cam off to have it re-ground by a reputable shop (I have heard good things about bulletcams.com, for example). Tell them about your car and other engine mods, and intended use, and they can hook you up with a bumpstick that'll make you happy. You may need new springs and pushrods too (Bullet should know this). It should cost about $175-$200 for Bullet to regrind your cam, plus any additional cost for springs/pushrods.

5. If you want still more power, now it's time to get into the heads. If you have gotten to this point, it probably will have been cheaper to just swap in a 350. You can do some cheap mods on the heads though that can help. A simple polish job on the ports is easy enough to do and should help out noticeably. Get a 3 or 5 angle valve job done on your valves. If when you take the heads off you discover that you need new valves, get the next bigger size. Don't go wild, again you have a small engine that you are trying to maximize torque with. You can have the heads professionally ported and polished and rebuilt but again it's probably not worth it in your situation.

Sorry for the long-winded post

To sum it all up, in addition to the exhaust and air cleaner you have on the way, be sure to get long-tube headers of the right diameter and gasket match them to the exhaust ports. If you still want to spend some money after that toss the emissions carb and intake.

 

Save your money and drop in a 350. You can spend a fortune on the 307 and still not get what a 350 has stock. I have a 305 in my Cruiser, but if it is ever replaced, a 305 won't go back in.

 

^^^^^^^^^
What DG said.
You will chase power forever with that 307 and dump money into a fruitless pursuit. The biggest problem with them is the cam and heads and that can get expensive. Those heads have intakes about the size of a pencil lead. Trust me. By the time you dump money in that 307 and get a little more power....you could have dropped in a 350 or 455 and had tons MORE power.

 

Unless you do a lot of highway driving a gear change might be a good choice for you. Chances are your ratio is way low for fuel highway fuel economy numbers.
"Adding a little gear"(higher numeric ratio) will improve pick up dramatically.