I rode a bike with a 13-15-17-20-23-26-30 seven speed for years, so if you wanted to get some closer jumps (and if this cassette is still available) with a smaller granny you might get nicer closer jumps and still low enough of a low gear for you.

you would have to do a gearing chart to see what this would give with a given new granny, and maybe its not possible to find this cassette anymore, but perhaps its an alternative for you (lets say if you needed a new cassette anyway and were going to change the granny)

my old bike in question had a 24t granny and 40t midring, so a 16t jump which was ok but not great, but gave me the lower gears I wanted with the existing 13-30 cassette. For you a 26 granny would give you a 16t jump to your midring, I wouldnt go smaller than a 26 granny from my experience.

re your oval rings, too bad it wasnt 20 years ago as I could have not thrown out my biopace gears and given you the 28 that was on my bike.....(hated them so much I threw them out)