Got a chance to open up the rear rocker box to replace the tappet guide and pushrod cover o-rings, adjust the pushrods, and replace the rocker box gaskets. Second verse same as the first (or front in this case).
Had to cut down a 3/16″ allen wrench so I could get at one of the rear rocker box cover bolts.
The tappet blocks are marked: RI for rear intake and RE for rear exhaust (the front ones are marked FI and FE).
Replaced the o-rings on the tappet guides. All four, front and rear, were leaking between the block and the case. This should fix that. Again used a little assembly lube to carefully install the o-rings without having them twist up.
Replaced the o-ring between the case and the tappet block and reinstalled the tappet guides. Replaced the bolts and torqued everything to the proper specs.
Replaced the o-rings and seats on the pushrod tubes.
Cleaned everything up and installed new gaskets. Got the rear rocker box all buttoned up and tightened down to the proper specs. Adjusted the rear pushrods. All looks good.
Carb, tank, and coil put back together. Static timed it again.
Have some traveling to do for work, so it will be a couple weeks before I get to tinkering with anything else.