Which scope rings for matchdot 2

Any recommendations for scope rings to mount an ultradot matchdot 2 on a Clark rail equiped 1911 in 45acp? The rail is 5/8 " wide. Looking for something horizontally split. Is aluminum strong enough for a slide mount?

Aluminum is fine. Just do not over tighten the screws. Get a low mount ring and you’re good to go.
Jon

I like weaver 48364 for 30mm tubes. Aluminum is plenty strong, just be sure to tighten the machine screws as evenly as you can.

I have a 1" tube. Will the Leupold Rifleman series work or are they made for .22s?

You want rings that will fit a weaver style rail. 22 rings are like a 3/8” dovetail, much smaller. Not familiar enough with the leupold line to give explicit suggestions.

I would NOT recommend a 22 rail for a scope mount on a 45.  There’s way too much impulse to the slide in a 45 and that goes directly to the scope and rings.  The little dovetail doesn’t have enough grip to hold.  A Weaver or Picatinny rail will work much better

I have used the Leupold Rifleman rings on both 45 and 22s.  I am currently using Leupold PRW2 low rings with my Matchdot.  A bit heavier (4.75 ozs/pair), since they're steel, but repeatability when I remove & reinstall the Matchdot is excellent.  The B-Square aluminum version of that ring (pictured, on right) only has 1 crossbolt, but only weighs 2.1ozs/pair.  I have also used the Vortex Pro-series low rings (3.45ozs/pair) as pictured on my backup Victor.  By comparison, the as-equipped Ultradot rings (pictured on left) weigh 1.7ozs/pair.

This is where I go to select scope rings:

Amazon - Scope Rings

As noted by Jon, they come in different heights - I always try to pick a "low mount".  Then there is a choice of "two screws" or "four screws".  I used to prefer 4, but for a light scope, 2 seems to be plenty.  

Dave Salyer strongly suggested I switch. from 30mm to 1".  So I now have two 30" Matchdot II sights that I ought to sell here.  The 1" sights worked better for me, and are lighter.  These are the rings he suggested I buy, which I now have on my 1911 45 Salyer/Springfield:

Leupold Rifleman Scope Rings 

They won't work for your Matchdot II though, as you need 30mm.
I think these are what I used to buy:  Leopold 30mm medium
They have four clamping screws, not two, which is likely better for a 1911 45.