Flatgate is correct: according to Dougan's book on Rugers the 22 bore was standardized at about serial number 150,000, in 1960 and have been the same dimension for single cylinder guns as for convertible (dual cylinder) guns ever since. If by "long barrel" you mean a 9 1/2", Ruger never catalogued a Bisley with one as far as I can determine from my catalog collection. If you mean a 6 1/2", that was the standard length barrel for the Bisley .22s. If you did find a 9 1/2" barreled Bisley and verified it as produced and shipped in that configuration, it would be so rare and valuable that you wouldn't want to shoot it.
So what options are you left with? Sometimes you have to make want you want. Custom gunsmithing is an option but expensive. The easiest solution to your desired Bisley .22 configuration is to acquire a used standard Super single six (has adustable target sights), with a 9 1/2" barrel and swap barrels with an adjustable sighted Bisley 6 1/2". I believe the Bisley barrels are marked as such so if you're a purist you may not like your barrel being mismarked. But if you just want a shooter, you'll have what you want. And having a gunsmith do a simple barrel swap for you would be relatively inexpensive. The other advantage is that since Supr single sixes are all convertibles with few exceptions, you'd have a dual cylinder, 22 LR and 22 WMR Bisley which I don't believe was ever offered. You could then sell the standard gun with 6 1/2" barrel to someone just looking for a shooter , not a collector gun and recoup the cost of the extra gun or give it to your son, daughter or grandchild.
Another option is to purchase a Bisley grip, hammer and trigger and make your own out of a standard 9 1/2" Super single six. Parts would be under $200 and it's a bolt on operation. You wouldn't have the unique Bisley engraved cylinder but you'd have a mag cylinder also.
Super single sixes with 9 1/2" barrels are not hard to find on gunbroker. There's a couple listed now. If you get one with a little use and wear, the collectability value is low (although they are not that uncommon in recent production guns) and you wouldn't have to pay a premium. Actually used 9 1/2" guns don't sell all that well and can be had for less than a more common barrel length in many cases. Just food for thought. Good luck.
