Thought I might join in here since I'm a 1/4 of a way through a stroker build .
I started a blog on what I was up to here: http://datsun-240z-blog.viczcar.com/
As mentioned above to build a stroker right takes a lot of money and patience. You are right in that it keeps with the originality of the car and one of the things I love so much about the Z is the L-series engine, there just so fun to work with and look fantastic all polished up in the engine bay with triples hanging off the side. Not to mention how lovely a well sorted one will sound. Yep they do have lots of torque and its a great feeling when you launch a well sorted one.
The biggest obstacle for me is the money it takes. I bought a LD28 crank for $700 + shipping and that's before any machine work such as balancing / shot peening or heat treatment. Then you want to get yourself a set of L20 rods or L14 rods (even rarer - read expensive). L14 rods are rare because they never came out here and they were found in a 4 banger which means getting 6 is hard. Not to mention everyone wants them for their ideal rod / stroke ratio. You can also use L20 rods but they are getting harder to source.
You can stick with standard L28 rods but you will loose a bit of power and it will make for a bit of a pig IMHO. Then there's custom pistons (you can go cheap - but after investing so much already why?) You need to get block work done, cylinder head work, valves, cams, rockers, lash pads.
The list builds and the more you do the more it feels like you should do. You could easily pump 10 - 15k in a motor. That's before even considering turbo chargers. A guy in SA has built a stroker turbo Ben is his name. He's floating about somewhere - not sure if he's a member here now. I think you can find him on the Zgarage (I always forget the link - look in our links section).
Of course if you want NA you can get a set of Triples or F.I of course more money there too .
Lately the idea of an RB26 in my Z has been rattling around in my mind. Its a good thing I'm overseas at the moment because I might do something silly . Different horses for different courses it all depends on what you want at the end of the day.
You can also check out Eiji's cool Z which runs an L28 http://www.viczcar.com/Featured-Rides/Eiji-Hosomi-s-Datsun-240z.html
He's pushing close to 350HP at the flywheel or at least I believe.