Which year or years 360 is best

As an aside, I've had really good luck with my Magnum engine. There are a couple of little details that make the swap slightly more complex than a standard 360, but the Magnum makes more power OOB than a standard 360 (and my shortblock is straight out of the wrecking yard, runs 11s in a 3400 pound street car), and they've got good aftermarket heads now, so you don't have to run the cracky factory junk.

With the availability of the Indy X heads I wouldn't really worry about running magnum heads on an LA block. They are cheap, good heads without any of the rocker conversion headaches, or stock magnum head cracking issues.

If you're looking for a 90% street setup, I wouldn't worry too much about getting the best year block strength (OBVIOUSLY have it checked before you spend money having it machined). You just aren't going to put it to the kind of stress thats going to break even a bad one, and you're not going to bore it more than .030 anyway!

That strength stuff is mostly for racers to worry about. They are going to see lots of high rpm and cylinder pressure, and want a block they can go back and bore a couple of times.

Again, for a street setup, being able to run a hydraulic roller cam (without a bunch of machine work or expensive lifters) is going to pay WAY bigger dividends than block strength.

Hydraulic roller = More power and torque over a wider range in a streetable package, no worrying about lobes going flat, or zinc in the oil or any of that crap.

Where are you located?

Steve