While you doing the short block assembly and degreeing your camshaft, setting the valve lash etc.be sure to find true TDC and check the front Dampner / Balancer Mark is right. Degreeing the cam make sure it matches factory specs or is sliaghtly advanced. You might also want to paint that mark with some white paint to make it easy to see with your timing light. Some G Series Info I have collected is posted below maybe there is something of help. Best of luck.
1941 to 1947 226 Cu. In. G Series Flathead Inline Six's, 90 Horse Power @ 3300 RPM, 180 Torque @ 1200 RPM
3.30 Bore X 4.40 Stroke, 4 Main Bearings, Compression Ratio 6.8 to 1, Cranking Compression 105 to 125 PSI
Holley Model 847 F 1V Carburetor, Firing Order 153624, Normal Oil Pressure is 30 Lbs. @ 2000 RPM, 6 Volt System
These engines respond well to a good multi angle (4) valve job with back cutting of the intakes blending of the valve bowls, exhaust valves can benafit from a slight bevel cut or radius on top edge of valve.
Stock Tune Up Specs in Order
Stock Spark Plug were the old Champion H10, Alternatives you can check out are Autolite 216, 4316, MP4316DP, Motorcraft AL5, AL7CF4 if you can find a Copper Core one that might work real nice. There used to be some nice Mallory and other brand ignistion Coils available.
1. Spark Plug Gap .025 you could try up to .030 if you have a good enough coil
2. Basic Point Setting .014 to .016
3. Point Dwell Setting 36 Degree's
4. Base Ignistion Timing is 1 Degree BTDC Vacuum Line unhooked and plunged.
5. Check that you Carb's Choke Operates Properly. Warm up the Engine Good & look to see the Choke is Fully Open
6. With the Air Cleaner Installed, Set the Idle Mixture Screw to Highest RPM or Vacuum Reading, Vacuum Reading should be 18 to 20 HG. At Idle RPM
7. Set the Curb Idle RPM to 475 RPM (Stock Trans or any other Manual Transmission) if you happen have adapted a C4 or another Auto Trans the curb Idle RPM is set to 500 with trans in Drive & Park Brake Set or have someone stepping on the brakes for you. I usally recheck the above number 6 & 7 settings a least a second sometimes even a third time to see if fine tunes it anymore. You could also try setting the Carb's Mixture screw to the "Lean Best Idle" which after you do the above setting you just turn the screw in 1/4 turn (leaning mixture some) that might give a better idle or off idle take off response.
Check that your Vacuum Advance Canister will hold a steady Vacuum without changing the distributors point advance plate position if not it needs to be replaced? Distributor Advance starts at 1/2 a Degree BTDC with full advance of 9 Degrees BTDC at 1250 RPM. Base Timing is Advanced or Rerarded by adjusting the Vacuum Break Set Screw on the Distribitor Housing. The Point Condesor Capacity is .21 to .25 MFDS. Points Spring Tension measures 20 to 24 Oz.