The 260 gives up a lot of torque to a 289, let alone a 302. But they share the same stroke as a 289, and don't mind revs so with steep gears in the back you can be fast-ish? Ford used them for their indy cars and made big power back in the early 60s with some exotic parts. Keep in mind, even though you CAN rev them to 6500+, you'd need solid lifters and a cam to make that worthwhile, and it would hurt your already sad low RPM power even more.
Arlington, the bore in a 260 is 3.80, compared to a 289/302 which is 4.00 Are you telling me you bored a motor .200, and it somehow lived? Because frankly, I would have said that wasn't possible. That's not .020 over. .200 over. With sleeves, I guess it could be done, but that's pretty pricey!
And that brings everything back to the start. The 260's smaller bore makes it impossible to use big valve heads, because they'll physically run into the edges of the bore, or at least be shrouded to the point where they don't work well. So, stock 260 heads with little valves. And using the stock heads means a stock intake or crazy problems trying to neck down an intake to the tiny ports. The bellhousing pattern is 5 bolt, so most transmissions won't bolt up.
Bottom line? This is a good engineering problem for masochists with deep pockets, but not such a good motor to hotrod, compared to the good ol' 289 or 302 (which are, to all intents and purposes the same motor in most regards).
If you have one in good shape, as I did in my '64 Fairlane, it's kind of cool in a monocle wearing, tip-your-hat-to-the-neighbors as you go by on a Sunday drive sort of thing. I would definitely treasure and try to keep one in good shape if you have it. They're rare now! But if you want to go fast, you'd sure get better results and save a bundle by getting a later model motor. And if you get a twinge of guilt about it not being the original motor, put on the stock air cleaner and valve covers. Few people would ever know the difference.