What camshaft for my 258

For gas mileage go with any low/mid range cam. The Clifford 97-2021-K Jeep & AMC 199/232/258 Cams & Kit 264H would be an even better mileage choice. The 280 is pushing it as far as lift with stock springs, it's right at the limit with 0.498 lift. 

farna wrote: For gas mileage go with any low/mid range cam. The Clifford 97-2021-K Jeep & AMC 199/232/258 Cams & Kit 264H would be an even better mileage choice. The 280 is pushing it as far as lift with stock springs, it's right at the limit with 0.498 lift.

I certainly can't complain about my cam - I mean and Eagle with 24 mpg average with most of it in-town commuting miles with only 10 of each trip being highway, at 45 mpg speed limit?
That's AVERAGE over 2 tanks. And it's got plenty of low-end. Can take off in second gear, and it takes a bit to "lug" it. (of course shaving .020 off the head didn't hurt)

Frank - how did you get so deep in knowledge about the early 6s and the very old Ramblers?

The two numbers appear to be the same thing. You'll have to call Clifford and see if there is a difference. You also need to figure out what you want to do with the car. One of the descriptions states "peak hp at 5300 rpm". If this is a cruiser, forget that cam!

The Clifford 272 is much better for a street car -- 60% of peak torque off idle, max hp at 3500 rpm. Most cruising is in the 2000-2500 rpm range with a six (should be anyway, higher rpm just burns more fuel). You should only hit 3000-3500 when passing or during other rapid acceleration. Peak hp @ 3500 doesn't mean it stops producing power at 3500, it should still produce good power for another 1000 rpm (4500). It just won't produce MORE power over 3500 -- power will start to drop off, and probably  fall off completely around 4500-5000 rpm (it will just stop pulling).

The 264 is probably best for a street car -- 80% of torque off idle will produce good gas mileage as the engine isn't working very hard just to get the car moving. HP peaks a bit high at 4300 rpm, but the TORQUE PEAK and how much torque is available at low speeds is the most important factor for a street car. This cam has a broader rpm range than the 272, according to what Clifford says.

Compare these cams with Comp Cams. You will find similar performance claims for similar duration and lift. The Xtreme Comp Cams are a bit aggressive IMHO for a street engine with stock springs. Lift needs to be under 0.500" for stock springs. If you go with one of the Clifford cams find out about the springs they send first. I'd use a 264 or 272 with stock springs for a street car. If you intend to continually run it over 3500 rpm you will need stronger springs. I suggest the Mopar Performance springs if you go for stronger ones. They will be sufficient for the 264 or 272 and still not so strong as to need additives in the oil or racing oil. They are just a bit stronger than stock (they are stock factory springs for Magnum V-8s). If you use heavy springs like Comp sells (no way I'd use the Comps in anything but a full race engine!) then you will have to run a high pressure additive (ZDDP additive, or break-in additive) all the time, or use off-road/racing oil. Diesel oil has a little more than regular gasoline engine oil, but even that has been reduced in recent years and isn't recommended to be run without additional additive with heavy springs (such as the Comp springs). You need a break-in additive when initially breaking in a cam no matter what, and I run it in the next oil change just to be safe. After that you're safe with normal oil for normal driving and stock (or near stock) valve springs.

Price is the same for both though. I think they may have changed numbers and just not updated the site, that or they forgot to update the prices.