Well, at $65 this is really a bargain only if you can repair the pistol yourself. If you can find a more-or-less correct S&W hand for $20 (with s&h) you are already into this for $85 before doing anything else. If you have a gunsmith modify and fit the hand, you may find your final cost approaching or exceeding the cost of a WWII S&W Victory in .38 S&W.
If you pursue this, the first thing is to identify which S&W model this copies. Spanish copies of S&W revolvers vary widely in how closely they copy the original, especially in the lockwork. I'd start with
http://www.oldwestgunsmith.com/gunparts/swhome.htm to compare it with various S&W models and versions, especially the K-frame models. You can also find an exploded diagram of the S&W model 10 (1950s+ version of the S&W Hand Ejector model 5, aka Military & Police, aka Victory) at Numrich:
http://www.gunpartscorp.com/catalog/Products.aspx?catid=10016. Note that a few parts are different on the model 10 versions than on the WWII and earlier revolvers.
One of the problems with replacing parts in revolvers is that this can entail a little or a lot of handfitting to get the revolver's action to function correctly, and the hand is an essential part of the action. Using an S&W part in a Beistegui Hermanos copy will almost certainly require handfitting.
The "38 CTG Long" may refer to the .38 Colt Long or to the .38 S&W Long cartridge. While there is no actual .38 S&W Long, it is a designation frequently found in connection with older European revolvers and ammo. You can Google "38 S&W long" to find discussions, descriptions, photos, and dimensions of the cartridge, but be prepared for German, Italian, Spanish, etc websites (or use "Google translate").
Finally, whatever the actual size of the cartridge, remember that many older Spanish revolvers were intended to be used with relatively low pressure black powder cartridges rather than the higher pressure smokeless powder cartridges that replaced them, much less the even higher pressure cartridges available today. Since these Beistegui Hermanos copies are fairly well known, you might want to check with some owners to see what cartridges are appropriate (and maybe even find a BH hand, although that would still require some handfitting).
Good luck!
Bill