Good News for You!
I have a similar Ashwamegh 25/2 w/ ST12 head. Last night we had a wind storm and the power went out a couple of hours before bedtime.
I just lit a pair of ISO-Butane camping lanterns so we could read books (remember those?) before bed.
BUT! Today I went to the garage and inspected / pre-lubed the Listeroid and lit it off for the first time in about 4 years. It took right off!
I ran it @ 3Kw on space heaters for an additional hour after the water temp got up to 200F (93C?)
I want to caution all of you twin operators that the 'off side' injector pump cam follower and the end of the cam run very dry. That housing does not have a supply of oil, so I plumbed in a pipe tee at the top of the oil pump and run a hose to a Frantz oil filter an direct the filtered oil into a fitting that dribbles onto the 'dry' cam. This cavity has a drain hole to allow oil to return to the sump.
I have added oil pump discharge pipes, out the block to an oil heater (small marine transmission oil cooler) that resides on the hot jacket water 'up' leg. Then a full flow oil filter and back into the block to dribble onto the 3 main bearings.
Now the oil is heated & filtered so I don't worry about using detergent oil.
I went thru the governor spring routine, as with you, the final result was good. I'll be looking into the 'full governor travel' George mentioned.
My 25/2 was set up and run at 1000 RPM initially, but it was pretty twitchy, and with the poor governor springs would overspeed when load was reduced. It shook so bad it broke mount bolts and was generally scary. I considered that too be too risky so:
I got a smaller gen-head pulley, which reduced engine speed to about 735 RPM (too bad, smoothest was about 910 RPM, but no pulley available in that size) My measured Max Output is 9.6Kw blowing black smoke and squeaking the drive belt!