I have a low compression 350. It dynoed at 207hp at the rear wheels. Eventually I want to go with more Hp, but in the short term would a gear change to say 3.42 give me a noticeable kick? I currently have 2:73 gears. I would probably go ahead and have a posi put in as long as I'd have someone taking the gears apart. Thanks.

you'll notice the kick from the get go with that change although the actual RPM difference is only about 400, but at the same time you will lose top end speed, (shouldn't be noticeable for a street application.) This change will make the car scoot a little better, but won't give you the feeling of gobs of horsepower if that's what you're looking for. Also, you will find yourself stopping at the Petro a little more frequently. Jason.

More noticable with 4:10 or 4:56's.

I think that 3.42s would be a nice street gear.

I've got 4.10s in my 68, and it tachs 3200 rpm at 65 mph,
and 3.55s in my 72 and it tachs 2770 @ 65 mph.

Both have 275-60-15 rear tires.

In my humble opinion, you will feel a nice kick from the swap.

I would go with 3:55's or 3:75's and get a 2nd set a taller rear tires for long trips. Then you will get the maximum performance from the engine and for performance and the taller tires can be swapped over in 25 minutes for decent mileage.