As a former owner of a Buick 225 Oddfire V-6, I can explain why the TBI unit doesn't work with it. The oddfire V6's had 120 degree crankshafts, which made the left and right cylinder banks fire at odd times, since the V was 90 degrees. The engine would fire off one bank, rotate 90 degrees, fire off the next, and then rotate 150 degrees until the next bank fired, rinse and repeat. It ran a lot like a bunch of Harley motors in a gang. Because the cylinders don't fire in a monotonic pattern the TBI computer gets confused and doesn't calculate the RPM correctly. You can trick a TBI computer into running an oddfire engine by making a crank angle sensor to trigger it instead of using the ignition. Later GM V6's were even fire. A TBI setup for a 3800 V-6 should be easy to adapt to an inline engine, only the firing order is differant. Even fire V-6's fire every 120 degrees just like inlines.
