Well then let's put it this way;
a 7.25 will be destroyed by peg-legging it with a 340/4speed, and it won't take long.
an 8.25 open will last a lil longer. Without peg-legging it, it can last a lot longer. With skinny tires and a suregrip, she can last for years, in your application.
>>But because it's gonna be a 4-speed, and might get a 340, or more likely a 5.9Magnum, cuz just try to find a 340; Neutral-drops with a 5.9, and big tires will eventually kill the 8.25 so then, you might as well stuff an 8.75 in there now, while the car is in your garage, and you don't have to tow it home from some far-away place.
If you really want a 340, just put a 318 in it and glue some 340 decals on her. Who's gonna know. Oh and, install an overdrive, cuz a 318 does well at 65=1600.
But if yur just gonna cruise, then put a slanty in it and the 7.25 will be fine, exactly as it is. But, a slanty will not like the A833od, with 2.76 gears @65= 1600, in overdrive; so you're gonna have to gear it up. Which is not a bad thing except more money
IMO;
and I have to qualify it this way, cuz sureaschit if I don't somebody will call me a 318 hater, so
IMO
by far the best/cheapest combo for cruising, would be;
a 5.2M, the od box, and 3.23s. That would be 65= 1900. That could go mid 20s mpg on 87E10, easy-enough, more with a good tune, and now you can cruise it anywhere.
This is a combo on which I would install my Offenhauser Dual-Port, my 340 logs, and dual exhaust. My carb of choice for that DP intake, would be a Metering-Rod type, like, a TQ or a QJ.
The 5.2 with a metering-rod carb, and a dash-mounted, dial-back, timing module, will cruise down at 65=1600 with plenty of cruise timing, and I think I could get close to 28mpgs in almost any A-body. Maybe more with a fast-back. Normally I would recommend a 5.9, but for your stated usage, a 5.2 would be plenty, and if I did recommend a 5.9, I'd get raped again; so, I'm not recommending a 5.9, altho I would install one in my car cuz at 65 mph it won't make much of a difference to mpgs, but with 2.76 rear gears, you'll be glad to have the extra ftlbs at take-off. and, the 5.9 will easily pull an A-body at 65=1400, but try and find gears for that...... yur gonna need 2.45s, and taking off in first gear, even with a 3.09 low, is gonna be an exercise in patience.
To run the 2.45, you more or less need the A999 automatic, and a higher than stock stall; or an A518 auto. Unless you have a deep-low 5-speed manual. or a Commando with a GVod, used as a splitter. But
I would never recommend the 2.45 rear gear, except for straight cruising.
If you're serious about building a Cruiser; then leave the car at 318 or less, install 2.76s, and a higher than stock stall, around 2400>2800. and call it done.
