Chuck,
You don't need a stand alone speed feed calculator. Moreover there isn't one.
I think you have cracked it -950 rpm suits you, your feed, your cutter and your machine.

Don't worry to much about the (horrible) thump thump thump - it is just the action and noise of a single insert. I know it is a little off putting - but at least you now understand what your machine is having to put up with. (My machine is exactly the same).
The chips will come off hot and fast.
Cutting a dove tail is a difficult proceedure. Seems to me you have done it.

A smaller cut, with a faster feed may be benifical. Normally better than a large cut with a slow feed.
All this roughing out will save your HSS dove tail cutter no end.

Now when you come to use the HSS dove tail cutter reduce you speed to 500rpm. Just see how it goes first.
Keep the cuts small .005 see how it goes, with the feed test faster - slower.
I t is just a slow process Chuck - trying to not break the HSS dove tail cutter.
If all looks good increase the speed and feed if you want to, but just be carefull with the depth of cut.
The HSS dove tail cutter makes a nice noise - brrrm.....brrrm.....brrrm much more reasurring

DaveH