I admire you for keeping it original and for looking to do some unique stuff with modifying your 226. I'm in the same boat, and have been looking for parts here and there. Fortunately I ended up with a complete spare 226 that I've torn down to help with my efforts. But before anything, you have to remember this is an old motor, with a very long stroke and comparatively small bore. It was never made to rev high. Hell, its peak torque comes at about 1300RPM. If you rev and race this motor like a hot rod, you're likely going to make pretzels out of the rods. Now that doesn't mean that you can't modify it and get a little extra power, I'm just pointing out that you're not going to be churning out big numbers with this motor.
I decided to go with digital multiple spark ignition using an ignition controller. I use the Accel 300+ ignition system and have loved it. I'm not a big fan of MSD, and Accel's ignition boxes have been digital since the start (a lot of MSD's boxes are still analog). In my opinion, you pay for the name with MSD. The Accel 300+ will take the signal from your points and then fire your coil multiple times up to a certain RPM (the 226 won't rev that high of RPM anyways). The good part about this system is that if the ignition box ever fails, you just connect the coil how it was without the box, and move right along. I run an Accel super stock coil. The difference with multiple spark ignition is incredible. It cranks faster, idles better, and is more responsive. I preferred to leave the points. This way you can carry a spare set of points around and swap them out if there's a problem. If you run electronic ignition and it fails, you're SOL. I also run Napa Belden plug wires (I believe 7mm). I bought a kit for an early Chevy I6 and AMC I6 and used wires from both kits.
As far as carburetion goes, the Carter YF left a lot to be desired for me. I originally went with a 500cfm Holley 2300 2bbl, and after tuning it, it ran great. But it was really too much carburetor. I ran a 1bbl to 2bbl Rocester adatper, then a 2bbl Rocester to 2bbl Holley adapter. I now run a Holley 94 that I restored myself, and it's a great fit. I'm still working on a throttle linkage however. I run a 1bbl to 2bbl Rocester/Stromberg 97/Holley94 adapter. The adapter doesn't create too much of a problem at all going from the 1bbl hole to the 2bbl carburetor. With the Holley 2300 I did have to really step up the accelerator pump, but with the smaller Holley 94, it was real easy to get it running good. I also like the nostalgia of the Holley 94/Stromberg 97.
They make a 2bbl factory intake manifold that they used on some wagons and pickups. This was also used on some Kaiser and Manhattans with the L6-226. These are fairly easy to find, at about $50-100. I've seen one Continental/Kaiser Edmunds 226 aluminum head on eBay that I bid on at the last minute and lost. I believe it sold for about $350. I have yet to see one since. As far as exhaust manifolds go, that's going to have to be a custom job. The only Offenhauser hardware I know if is for more recent Jeep AMC I6 motors.
In my opinion, it's really best to go with a stock rebuild and then do a lot of bolt-on external upgrades. Multiple spark ignition, a hot coil, good plug wires, and a 2bbl carburetor have made one hell of a difference over stock.