On Cointakers site, youll need their 2 LED (Twin 2835).
Its 1mm narrower, and should work.

On rare, but definite cases, some Gottliebs were drilled as small as 10.5mm,
as opposed to 11-12mm.

I have run into this issue with Gottliebs. I used a dremmel sanding disc to knock the ring down a bit. Just be careful not to go too far into the lamp.

The ones from Titan fit my Black Hole and Haunted House. The 28 volt ones under the playfield I got from K's arcade.

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I had the exact same problem with my Super Mario Bros.
The top of my lamp sockets are just about flush with the bottom of the playfield, so the LED has to get all the way through the playfield before they can engage the socket.
I measured the diameter of the GI holes in my playfield at 11.80mm.
My playfield measures 13.27mm thick.
The top of the socket is 11.20mm below the top of the playfield.
I've got Cointaker LEDs, and have measured their frosted 44 as having a 12.08mm OD, and the regular 44 LED as 12.02, so neither will fit.
The socket is low enough below the playfield that the ring on the Cointaker LED hits the playfield and can't engage the socket.

Someone recommended the following Comet LEDs to me, with a 10.91mm OD, and they fit perfect and worked great.
http://www.cometpinball.com/product-p/1ledbullet.htm

Sorry I don't have pictures of it with the lights out. I've got a video somewhere but can't find it right now.

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Very pretty. I highly recommend converting the lower playfield GI to the standard 6.3 volts -- modern LEDs are more than bright enough!