ring and pinion ratio suggestion

RustyRatRod said

Would you mind telling us what "car" this is?

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It's a Chevrolet Opala, first gen. I didn't say it because the first reply I get is 'did you mean Impala?' and it was made looking like this only here in Brasil. The info on wikipedia is not 100% accurate, but it's basically there if you wanna take a look. Mine looks like this, minus the square lights in the front, the mirrors are round chromed, and my color is a way darker metallic brown:

AJ/FormS said

That cam is about the same as a factory 340 cam, with some extra lift. So what you seem to be ending up with is a warmed up teener with a possibly ever so slightly, soggy bottom end with just a 9.4 compression ratio.(EDIT; Naw, I changed my mind, the Dcr comes in at about 7.8@155 psi. I don't see that as soggy at your weight and with a reasonable rear-gear.)The 2.92 low gear will help,as will the light chassis, and the H-pipe. IMO this cam will want a starter gear of around 10. I'm guessing 10/1 will be sufficient. That means a rear gear of about 3.42.
Since you offered options of 3.31 and 3.54, the final decision may have to be the hiway revs..
3.31s will cruise at 65=2670, 3.54s at 2860. Both with 27s. That is to say about 190rpm difference. I have cruised at both rpms and many others. With a good 3-pass muffler and full exhaust, this is no problem as to noise, just make sure the exhaust does not exit under the car.
This engine will be capable of great fuel mileage, and with the 9.4Scr, and about 7.8 Dcr, you should be able to run some pretty low-octane gas in it, at least on the hiway. To that end,when in doubt, err on the conservative side,3.31s in this case. With such a light chassis, you will want some bigger tires under there, to try and grab traction. If you can fit 28s in there, then you can run the 3.54s, for 65=2760rpm, right up the middle!
BTW
That's a real nice tranny; the splits are pretty even at right around 70%. What's that come from, and is there a bellhouse to bolt it right up to the engine?

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First, thank you for the well writen, well explained and complete answer. I wanted that info about exhauts, noise at rpm and what you said clarified.
-About 28" tires: here it's hard to find tires for these cars. I have 245/60 R14 (25.6" diameter) I mentioned and thought a good alternative was to buy 235/60 r16 (these are not that expensive, both wheels and tires). These measure about 27.1" diameter.
-Fuel: 'pump gas' here are E27 (27% ethanol, 73% regular octane gasoline). I don't think CR will be a problem at all. Thought about raising it up to 10, but I don't want to mill the heads and everything else.
-Transmission: Isn't it a nice ratio? Here we've had 1 good, strong transmission project/design called Clark 260F with many ratios.
Clark is the brand, the number is the torque rating 260 lb-ft and F if 'Four speed' (there is also a 'T', 3 speed). Although the rating looks low, it actually withstands a lot more. People usually drag race it with turbo cars.
So this 4 speed had:
-my ratio on Ford Maverick GT (302 V8);
-a close-ratio on all 4 speed V8 Dodges, and all V8 Dodges were 318s.
-and pick-up wide-ratios for both Ford and GM, inline 6, diesel, no V8 though (I believe more than 1 ratio).
The differences were the bellhousing, the input shaft is different for each ratio and the input shafts lenght. So I'll have to make the input shaft about 1" longer to fit the 318 using the Ford ratio.

Sorry I went too long again.