I used a base like that for my ultra bell and it worked fine just the total ht of the gage is smaller than the hole and enough movement to measure the min/max.

https://www.amazon.com/Supermotorpa...ng-0-15-0/dp/B07YYV2H6V/ref=sr_1_7_sspa?

here ya go.

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I have a tool I designed that might work for you. It has a 6 bolt flange and I use for all my bellhousings. If you want to use it send me a PM with your address I'll ship it to you.

Gus

the indicator you have appears to have the same size shafts. [remember, my eyes are not the best any more]
can't you attach your indicator to the main shaft using the clamps you have ?

https://www.amazon.com/Supermotorpa...ng-0-15-0/dp/B07YYV2H6V/ref=sr_1_7_sspa?

here ya go.

I have the same one you ordered and it works just fine.

The base does not need to be mounted dead center on the crank - I don't know why people think it does. You can mount it right out on the flat surface of the flywheel, it doesn't matter. The dial indicator will be in the hole and all that matters is that IT is roughly level with the flat surface of the bell and, for lack of a better term, square to the edge of the hole. And it also has to point in the direction of the base.

Here is the set up that I use. I had to build it myself since I couldn't find anyone who sold a tool that worked with my parts.