first time vaccum pump user and was looking for a good idea for the dipstick? thanks. Birdtracker

Look for a dipstick with a seal, pretty common on late-model stuff.
Obviously long enough you can calibrate it.

If you want to eliminate the vacuum leak then you'll need to buy a sealed dipstick.

Drill and tap the hole and plug it. Why do you need a dipstick?

Calibrate the pan before installing it. Calculate filters, accusumps, etc. Put oil in it less a quart or so and race it.

Mine uses a late model Jeep dipstick and tube cut down. It O ring seals.
Doug

I use a vacuum cap on my stock dipstick tube with a small hose clamp

I used a Milodon billet/braided dipstick/tube on my lowdeck stroker and with vac pump, and reached 20+ “ vacuum before adjusting down to lower levels. It sealed up very well. I think it was pn 22070

Is that the one that has two O rings on the male part that sticks into the block?

I don’t think this one has oring on the part that goes into block, but I used the Right Stuff to seal it up well. The dipstick does have oring.