Joined: Jan 2010
Posts: 9,831
Likes: 1,809
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
That trauma to the teeth isn't what is preventing quick shifting up to the big ring, but I would check and correct the tip of any tooth that is asymmetric left-to-right.
The teeth don't look heavily worn to my eye.
It won't hurt to test-install a newer chain, to see how it works. A KMC X-series chain is great quality for low price.
I've always equated the Maxy taper to the Suntour VX taper (also made by Sugino), and to the common JIS taper.
I often choose to use a bb with a bit less driveside offset on bikes of this type, this allows fuller range of the freewheel's gears while in the big ring so less downshifting in front for me, especially if the freewheel has a good 30t or so big cog.